ProspectTilt · Pitch Intelligence
PitchIQ
Z-Contact% · O-Swing% · SwStr% · K% · BB% · EV · LA — All Four MiLB Levels
What it is. Filth+ grades a pitch's ability to miss bats from its physical characteristics alone — velocity, induced vertical break (IVB), horizontal break (HB), vertical approach angle (VAA), release height and side, extension, and spin rate — plus its velocity and movement differential off the pitcher's own fastball. It is scaled so 100 = average and every 10 points = one standard deviation, against the full pitch population, so grades are directly comparable across pitch types. Filth+ is the first bat-missing model built natively for minor league arms, including the Complex League.
How it is built. The model is trained on 2.24 million MLB pitches with full Hawk-Eye Statcast tracking, conditioned on swings only — because location, not stuff, drives whether a hitter offers at a pitch in the first place. Following the approach Eno Sarris originated with Stuff+, we train a separate model per pitch family (four-seam, sinker, breaking, curve, changeup, cutter) to predict the probability a swing comes up empty. The single most important feature — consistent with the public literature — is each offspeed and breaking pitch's velocity and movement differential off the pitcher's own fastball. VAA is computed from full trajectory vectors identically to the rest of PitchIQ, so MLB training and MiLB scoring measure the same physical quantity.
Train on MLB, apply to MiLB. The model learns what makes a pitch nasty from the cleanest data in existence (MLB Hawk-Eye), then applies that physical standard to every trackable MiLB pitch. This is legitimate because bat-missing is physics — a 95 mph fastball with elite ride and a flat approach angle misses bats at a predictable rate regardless of which level it is thrown at. We are not claiming to out-predict Eno Sarris's Stuff+ on MLB arms. The claim is narrower and defensible: PitchIQ Filth+ is the only public bat-missing model calibrated for, and validated against, minor league outcomes.
Validation — and why this number matters. A correlation means nothing without a baseline, so we benchmarked Filth+ against the naive predictors a scout already has. Tested within pitch type (the fair comparison) against actual MiLB swinging-strike rate, on identical pitches:
• Filth+ r = 0.55
• Raw velocity r = 0.13
• IVB only r = 0.00
• Velocity + IVB combined r = 0.14
Filth+ explains roughly four times more of the variance in swing-and-miss than raw velocity, and IVB on its own carries almost no signal. At the individual-pitch level the relationship is cleanly monotonic: pitches graded ~90 Filth+ miss bats on roughly 17% of swings, ~110 on ~48%, and 120+ on ~78%. These are out-of-sample results — the model never saw a single MiLB pitch in training. The validation loop is the genuine edge: every night of new MiLB data tests the grades against fresh outcomes, and the model recalibrates as the sample grows.
Why only Filth+. We also built and tested a companion "Stuff+" intended to measure contact suppression — how weak the contact is when a pitch is put in play. It did not validate: against actual exit velocity and hard-hit rate allowed in MiLB, it showed no meaningful correlation, and Filth+ itself predicted weak contact better than the contact metric did. Rather than publish a number that fails its own test, we removed it. Predicting contact quality from pitch shape is a genuinely harder problem than predicting whiffs, and we would rather ship one metric we can defend in any room than two where one is hollow. If a validated contact model is built later, it will be added then — and benchmarked the same way.
Availability and limits. Filth+ requires pitch tracking, so it exists only at the Hawk-Eye levels — Triple-A, Low-A FSL, and Complex (ACL/FCL). High-A and Double-A lack the tracking infrastructure and show no grade. Grades on small samples are noisier; minimum-pitch thresholds apply for display, though because Filth+ grades pitch shape rather than outcomes, it stabilizes faster than results-based stats. As with all models, the grade describes the pitch's physical quality, not a guarantee of outcomes — it is a tool, not a verdict. A Complex League teenager carrying a 120 Filth+ slider is showing a physical trait the industry cannot see at scale. PitchIQ can.
What it is. A predictive layer on top of Filth+ that forecasts how a pitcher's bat-missing stuff ages, reported as a confidence cone rather than a single line. The principle is to age the stuff, not the results: a pitch's shape is a physical property independent of the level it is thrown at, so aging the grade sidesteps the competition confound that contaminates outcome-based minor-league aging.
How it is built and validated. The aging path is learned from three full seasons of MLB Statcast (2021–2023, 1,123 pitchers, 7,099 pitcher-season-pitch-type rows), every pitch scored with the identical production Filth+ model. We use the standard delta method — comparing each pitcher to himself across consecutive seasons, within pitch type, weighted by the smaller sample — which suppresses survivorship bias, yielding 3,224 year-over-year change pairs. Before trusting the curve, we validated the same pipeline against fastball velocity, the one aging signal the public literature has measured: it reproduced the known shape out of sample, including a −0.21 mph/year decline at ages 30–36, inside the published consensus. Component checks confirmed release geometry and approach angle barely move while velocity and IVB decline — exactly as physics demands.
The central finding, and the honest limits. Stuff ages gently: the Filth+ curve spans only ~2–3 points across a career (under ¼ SD), peaking near age 28. Aging is a refinement to a projection, not the main driver — a pitcher's current grade dominates. Individual pitchers scatter around the path at 2.04 Filth+ points per year, which sets the cone width. A multi-tick stuff breakout (e.g. a deGrom-style jump) sits ~2.8 cone-SD out, roughly a 0.3% event — the model places such outliers in the upper tail and quantifies their rarity rather than pretending to predict them, because their cause lives outside shape and age. Ages under 22 use a literature developmental prior (shown dashed); the MLB panel cannot directly observe pre-MLB development, and the aging shape is transferred to minor-league grades on the basis that bat-missing shape is physical and level-independent.
PitchIQ's zone classification is grounded in Ben-Porat (2018, The Hardball Times), which established that MiLB Gameday coordinate data contains meaningful zone signal: Triple-A vertical location correlates with MLB at R²=0.48, Double-A at R²=0.34, and horizontal location carries signal (R²=0.25) across levels. PitchIQ uses a tiered methodology that matches data quality to the tracking infrastructure available at each level.
Full Statcast tracking via Hawk-Eye cameras provides exact pitch coordinates in feet (pX/pZ). Zone classification uses standard MLB strike zone boundaries (±0.83 ft horizontal, personalized sz_top/sz_bot vertical per batter fetched from the MLB Stats API). Accuracy is equivalent to MLB Statcast.
Games are tracked by MiLB stringers using the Gameday pixel coordinate system. PitchIQ derives park-specific empirical zone boundaries for each of 80 parks: the horizontal boundary is set at the 8th–92nd percentile of called strike x-coordinates at that park; the vertical boundary from the 8th–92nd percentile of called strike y-coordinates. Called strikes and balls are classified directly from umpire decisions (100% accurate). Swing pitches are classified using the park-specific pixel boundaries.
Accuracy. Validated at 89.79% accuracy across 124,603 umpire-confirmed pitches. The remaining ~10% error reflects genuine umpire missed calls (~4–5%) and inherent Gameday coordinate noise — the practical ceiling for this methodology given the available data.
Why park-specific. Gameday pixel coordinates are not consistent across parks. Each stadium has a different camera position and zoom level. By deriving boundaries park-by-park from actual umpire calls, PitchIQ eliminates the camera calibration problem entirely. The umpire is the calibration instrument.
Jupiter, Clearwater, Fort Myers, Lakeland, Bradenton, St. Lucie, Tampa, Daytona, Charlotte, and Palm Beach have full Statcast/Hawk-Eye coverage. Zone classification at these parks is equivalent to Triple-A accuracy.
The same park-specific empirical boundary approach is applied to 20 non-FSL Low-A parks. For parks where only horizontal Gameday coordinates are available, zone classification uses horizontal position only — capturing chase tendencies on pitches off the plate horizontally. Ben-Porat (2018) confirmed R²=0.25 horizontal signal at the MiLB level. Non-FSL Low-A metrics should be interpreted as directional estimates with an expected margin of ±3–5 percentage points.
PitchIQ's park-specific system produces zone rates of 40.6% at Double-A, 41.0% at High-A, 42.5% at Low-A, and 43.6% at Triple-A (Statcast ground truth) — a spread of just 3 percentage points across all four levels. This cross-level alignment is strong evidence the methodology is correctly calibrated.
O-Swing% (Chase Rate). League averages: Triple-A 28.8%, Double-A 31.5%, High-A 31.0% — the slight elevation at lower levels is consistent with less experienced hitters expanding the zone against developing pitchers with less precise command.
Z-Contact%. League averages: Triple-A 85.2%, Double-A 81.3%, High-A 80.9% — directionally correct, with lower levels showing slightly less contact on strikes as expected given developmental stage.
PIIS. The Prospect Impact Intelligence Score uses both Z-Contact% and O-Swing% as primary inputs. With corrected zone classifications at all four levels, PIIS scores better reflect true plate discipline process rather than coordinate system artifacts.
Umpire error. Called strikes and called balls are not perfect — umpires miss calls at approximately 4–5% on boundary pitches. Park-specific boundaries therefore encode both the true zone and umpire tendencies at each park. For prospect evaluation this is appropriate — what matters is how umpires actually call games at that level.
Sample size stability. Early-season boundaries derived from 500–600 called strikes are reliable but tighten considerably as the corpus grows to 2,000+ by season's end. Zone metrics for players with fewer than 150 pitches should be treated as directional indicators.
Ongoing development. Park boundaries are recalibrated nightly as new games are collected. This system improves permanently with time as the calibration corpus grows through the 2026 season and beyond.
DVS is a nightly-updated composite metric for minor league hitters only. It combines five independent signals into a single 0–1000 score. Pitchers and MLB players are not currently included but are planned for future versions.
The five components: (1) Live performance — MiLB wRC+ (park-adjusted, league-relative) acts as a performance anchor multiplier. (2) MLB arrival probability — our MLB Probability Index (0–100) acts as a confidence modifier on the base score. (3) Age/level surplus — players younger than expected for their level receive an upside amplifier. A 19-year-old in Double-A is worth significantly more in dynasty than a 24-year-old at the same level. (4) Industry consensus — rankings across five publications (The Athletic, Baseball America, FanGraphs, MLB Pipeline, RotoWire) add a consensus bonus. Players ranked top-5 in 3+ publications are eligible for the Generational tier (950–1000). (5) Dynasty ownership — Fantrax roster percentage across 6,500+ players adds an ownership bonus. In a pool this large, 40%+ ownership for a MiLB prospect represents strong conviction from experienced dynasty managers.
Important caveat: A player ranked highly by multiple publications but underperforming statistically may carry significant upside not yet reflected in current numbers. DVS weights pedigree and consensus heavily for young prospects — this is intentional. The formula self-corrects as the season progresses and rankings update.
Tiers: 950–1000 = Generational · 850–949 = Elite · 700–849 = Top Prospect · 500–699 = Strong Prospect · 300–499 = Solid · Below 300 = Developmental
Update frequency: Nightly at 5am ET, after the comp engine (4am) and enrichment pipeline (4:30am).
ERA (Earned Run Average): Earned runs allowed per 9 innings. Sourced directly from the MLB Stats API official boxscore — same number you see on Baseball Reference. 100% accurate, official scorer determination. Tiers: Elite ≤2.50 · Plus ≤3.50 · Average ≤4.25 · Below Average ≤5.00 · Poor 5.00+
WHIP (Walks + Hits per Inning Pitched): The most stable early-season pitching metric. Measures baserunner rate independent of run scoring. Calculated exactly from our PA table and game log. Tiers: Elite ≤0.90 · Plus ≤1.10 · Average ≤1.30 · Below Average ≤1.50 · Poor 1.50+
xFIP (Expected Fielding Independent Pitching): Removes defense and luck from ERA by using strikeouts, walks, HBP, and fly balls with a normalized home run rate (lgHR/FB = 9.7%). The most predictive single-number ERA estimator available. A pitcher with 2.50 ERA and 4.50 xFIP is likely due for regression. A pitcher with 5.00 ERA and 2.75 xFIP is a buy-low target. Formula: ((13 × (FB × lgHR/FB)) + (3 × (BB+HBP)) − (2 × K)) / IP + lgFIP_constant.
K-BB%: Strikeout rate minus walk rate. The single cleanest indicator of pitcher dominance. Removes the noise of defense, park, and luck. Above 20% is elite at any level. Below 10% is a significant concern regardless of ERA.
SwStr% (Swinging Strike Rate): The upstream cause of strikeouts — the moment of failure before it shows in the box score. More stable than K% in small samples. 15%+ is elite. 10-12% is functional. Below 8% means the pitcher is living on defense and weak contact.
O-Swing% Induced (Chase Rate): How often batters chase pitches outside the strike zone against this pitcher. Elite pitch movers who tunnel and locate generate 35%+ chase rates. Average is around 28-30%.
Z-Contact% Allowed: How often batters make contact when they swing at strikes. Lower is better for pitchers. Elite: below 78%. Average: 82-85%. Above 88% means hitters are squaring up pitches in the zone regularly.
GB% (Ground Ball Rate): Ground balls as a percentage of balls in play. Ground ball pitchers suppress home runs, induce double plays, and project well as starters. Elite: 55%+. Average: 42-46%. Below 35% is a fly ball pitcher — needs elite stuff to survive at higher levels.
Barrel% Allowed (AAA and Low-A FSL only): Percentage of balls in play that meet the Statcast barrel definition (EV ≥98 mph, optimal launch angle). The ultimate contact quality metric. Elite: under 4%. MLB average: ~8%. Above 12% means hitters are consistently squaring this pitcher up.
Velocity is displayed as average (Velo) and maximum (MaxVelo) across all pitch types combined. At AAA and Low-A FSL parks where Hawk-Eye is deployed, these are exact Statcast measurements. At Double-A and High-A, velocity shows — because Statcast hardware is not installed at those parks.
Velo tiers (fastball average): 98+ mph = Elite (top 1%) · 96-97.9 = Plus · 94-95.9 = Above Average · 92-93.9 = Average · 90-91.9 = Below Average · Under 90 = Fringe. These benchmarks apply to fastball velocity specifically. Off-speed pitches will always register lower — a pitcher showing 85 mph average velo likely mixes significant breaking ball usage.
Why MaxVelo matters: Maximum velocity in a start or outing represents ceiling, not typical output. A starter who sits 92 and touches 96 has a different profile than one who sits 92 and maxes at 93. MaxVelo tells you what the arm is capable of — particularly important for young pitchers still developing.
Induced Vertical Break measures how much a pitch rises or falls relative to a theoretical spinless pitch subject only to gravity. Positive IVB means the pitch is fighting gravity — riding up. Negative IVB means the pitch is dropping faster than gravity alone would produce.
Why IVB matters: A four-seam fastball with 18 inches of IVB is generating significant backspin-driven lift. Batters expect the ball to drop at a certain rate based on physics. When it drops less than expected, the hitter swings under it. That is the rising fastball illusion — the ball never actually rises, but it arrives higher than the hitter's brain predicted. This is measurable, repeatable, and one of the most important traits in modern pitcher evaluation.
IVB tiers (four-seam fastball): 20"+ = Elite (generational ride, top 2%) · 18-19.9" = Plus · 14-17.9" = Above Average · 10-13.9" = Average · Under 10" = Below Average. Sinkers and two-seamers intentionally have low or negative IVB — they are designed to dive, not ride.
IVB by pitch type context: Curveballs have negative IVB (typically -8" to -14") because they dive hard with topspin. Sliders and sweepers have near-zero IVB because their movement is primarily horizontal. Changeups typically have 4-8" IVB, slightly less than the fastball they mirror, which creates the perception of the ball diving away from the bat at the last moment.
What it is: The angle at which a pitch is descending as it crosses the front of home plate. Measured in degrees. Always negative — the ball is always dropping at plate crossing. Flatter pitches are closer to 0°. Steeper pitches are more negative.
The physics formula (Chamberlain, FanGraphs 2022 — the industry standard):
vy_f = −√(vy0² − 2×ay×(y0 − yf)) · t = (vy_f − vy0) / ay · vz_f = vz0 + az×t · VAA = −arctan(vz_f / vy_f) × (180/π)
Where yf = 17/12 feet (front of home plate). All velocity and acceleration components sourced directly from Statcast at the point of measurement (y=50 feet from plate). This is the identical methodology used by Baseball Prospectus, and FanGraphs (Alex Chamberlain).
Why VAA matters: Hitters swing on an upward plane of roughly 10-12 degrees. A pitch with a flat VAA creates maximum mismatch — the ball arrives at an angle the bat is least prepared to meet. Every degree closer to 0° is a degree of deception the pitcher gets for free, independent of velocity. A 93 mph fastball with -4.0° VAA can be harder to square than a 97 mph fastball at -5.8°. This is the Bryan Woo effect — elite deception from geometry, not just raw stuff.
VAA is available at Triple-A and Low-A FSL parks only. At Double-A and High-A, VAA shows — due to the absence of Hawk-Eye infrastructure. A Low-A arm showing -4.1° VAA at 19 years old is demonstrating a physical trait the industry cannot see at scale. PitchIQ can.
Four-Seam Fastball VAA Tiers: Works best elevated where flat angle clashes maximally with upward swing plane.
-3.5° or flatter = Elite — generational. Tyler Rogers, Josh Hader tier. Top 2% of pitchers.
-4.0° to -4.5° = Plus — genuine deception, plays up significantly above velo grade.
-4.6° to -5.2° = Average — functional, needs plus velo or movement to miss bats consistently.
-5.3° to -5.9° = Below Average — gets elevated and barreled at upper levels.
-6.0° or steeper = Poor for a fastball — do not throw up in the zone.
Sinker / Two-Seam Fastball VAA Tiers: Opposite philosophy — steeper is better. Works low in the zone to generate ground balls.
-7.0° or steeper = Elite — true bowling ball effect, extreme GB%.
-6.0° to -6.9° = Plus — strong ground ball tendency.
-5.0° to -5.9° = Average — functional sinker.
-4.9° or flatter = Poor — sinker playing like a flat fastball, gets lifted.
Slider / Sweeper VAA: VAA is secondary to horizontal break. But steep VAA combined with elite sweep creates two-plane movement that is nearly unhittable. A slider with -5.5° or steeper VAA AND 15"+ horizontal break is elite. A slider with flat VAA is tunneling poorly with the fastball.
Curveball VAA Tiers: Steep VAA is the entire point. The pitch should dive through the zone.
-10.0° or steeper = Elite — true 12-to-6, disappears under barrels.
-8.0° to -9.9° = Plus — strong downward action.
-6.5° to -7.9° = Average — functional breaker.
-6.4° or flatter = Poor — curveball without enough depth to generate swings and misses.
Changeup VAA: Should mirror the fastball as closely as possible. The deception comes from velocity separation, not angle. A changeup within 0.5° of the fastball VAA is tunneling correctly. A changeup 2.5°+ steeper than the fastball is tipping — advanced hitters will identify it early.
Key factors shaping VAA: Release height — lower release point flattens VAA naturally. A 6'5" pitcher releasing at 6.5 feet gets flatness for free. Extension — every extra inch of extension flattens VAA. Logan Gilbert and Tyler Glasnow at 7.6 feet of extension generate perceived velocity 2+ mph above actual. IVB — higher IVB fights gravity and flattens the approach angle. Velocity — higher velocity reduces time in flight, reducing gravity's effect. Location — higher in the zone equals flatter VAA, lower in the zone equals steeper.
High IVB fights gravity so the ball drops less than expected. Flat VAA means it arrives at the plate on a shallower angle than the hitter's swing plane. Together, the combination creates a fastball that appears to rise even though nothing rises. The hitter's brain predicts a trajectory based on what it sees out of the hand. The ball arrives significantly higher and at a flatter angle than predicted. The result is a swing under the pitch — the classic elevated fastball whiff.
This is not velocity. This is geometry. A pitcher sitting 93 mph with 19" IVB and -4.2° VAA is generating a more deceptive fastball than most pitchers sitting 97 with average shape. This combination is what Driveline, Tread Athletics, and every elite pitching lab in the country obsesses over. At the MiLB level almost nobody surfaces it systematically. PitchIQ does — live, across all four levels, every morning.
The elite threshold: IVB ≥ 16" AND VAA ≥ -4.5° on the four-seam fastball. This combination at any MiLB level on a pitcher under 23 years old is a serious MLB projection signal. Use the metric filter to find them: set IVB ≥ 16 and VAA ≥ -4.5 on the pitcher leaderboard. The list will be short. Every name on it deserves your attention.
The tunneling principle: The most effective pitch combinations share VAA as long as possible before separating. A fastball at -4.2° and a curveball at -9.5° look completely different at the plate but can be made to look identical out of the hand through 40 feet of flight. The hitter commits to one trajectory and gets the other. VAA is the foundation of pitch tunneling — and tunneling is why elite pitchers dominate regardless of velocity.
Extension and the perceived velocity bonus: Every foot of extension beyond the rubber shortens the distance the ball travels before reaching the plate. A pitcher with 7.0 feet of extension is effectively releasing the ball 7 feet in front of the rubber — the ball only travels 53.5 feet instead of 60.5. At 95 mph that translates to roughly 2.5 mph of perceived velocity gain. Extension is a free velocity upgrade. In PitchIQ, extension is displayed for AAA and Low-A FSL pitchers. A MiLB pitcher combining elite extension (6.8+ feet), high IVB (16"+), and flat VAA (-4.5° or better) has a fastball that plays at the highest level regardless of what the radar gun says.
TiltValue is ProspectTilt's composite pitcher rating. It rewards elite strikeout rates, low walk rates, high swinging strike rates, low ERA, strong xFIP, ground ball tendency, and — at Statcast-equipped parks — velocity and induced vertical break. It penalizes high walk rates and poor ERA. Available in the dedicated TiltValue tab on the pitcher leaderboard. Minimum 15 IP required.
Formula components: ERA qualifier (up to +13 points) · xFIP qualifier (up to +10 points) · K% qualifier (up to +13 points) · BB% qualifier (up to +10 points, penalty for high walk rates) · SwStr% qualifier (up to +10 points) · K-BB% (×0.44 multiplier) · IFFB% (×0.25 multiplier) · Velo qualifier — AAA/Low-A only (up to +11 points) · IVB qualifier — AAA/Low-A only (up to +7 points).
Important note: Pitchers at Double-A and High-A are structurally disadvantaged in TiltValue because velo and IVB components (up to 18 combined points) are unavailable without Statcast. A High-A pitcher with elite K%, BB%, and xFIP will score lower than an equivalent AAA pitcher with the same rates simply because the Statcast bonus is inaccessible. This is a data limitation, not a reflection of pitcher quality. Always compare TiltValue within level, not across levels.
The Problem With Existing Metrics: Every advanced metric available to dynasty and prospect analysts was built for Major League Baseball. xwOBA requires Hawk-Eye Statcast unavailable at Double-A and High-A. wRC+ measures what happened, not why or whether it will continue. EV90 captures raw power but ignores contact decisions. K% and BB% capture discipline but say nothing about damage. No single metric has ever simultaneously measured contact execution, plate discipline, power sustainability, and swing efficiency across all four full-season MiLB levels — until PIIS-T.
The Formula: Raw PIIS = (Z-Contact% × BB% × dampened_ISO^1.5) / SwStr%. All components expressed as decimals. ISO is dampened toward league average based on sample size using a stabilization weight of k=150 PA — this prevents a player with 3 home runs in 30 at-bats from dominating the leaderboard in April. As plate appearances accumulate, the observed ISO carries progressively more weight. By 300 PA the dampener has minimal effect and observed ISO is trusted fully. The ^1.5 exponent on ISO creates meaningful separation between true impact bats and slap hitters without the extreme volatility of squaring. O-Swing% floor of 15% applied at Double-A and High-A corrects for stringer data coordinate limitations at those levels. Minimum 40 PA required. PIIS-T+ adds EV90: Raw PIIS+ = (Z-Contact% × BB% × dampened_ISO^1.5 × EV90) / SwStr%, available at Triple-A and Low-A Statcast parks only.
Component Breakdown: Z-Contact% — the foundation. Measures whether the hitter executes when pitchers attack the strike zone. The most stable early-season metric in PitchIQ, reliable after just 100 pitches. A hitter who cannot make contact on strikes is being beaten at the most fundamental level of hitting. BB% — the complement. Walk rate proves pitch recognition on the other side of the equation. Together with Z-Contact%, it describes a hitter who attacks strikes and lays off balls. High Z-Contact% without BB% is a hacker being exploited. High BB% without Z-Contact% is a passive hitter who is hittable. The combination is the signal. Dampened ISO^1.5 — the damage component. ISO measures extra-base ability independent of batting average. Dampening and the ^1.5 exponent together ensure power is real and sustainable before it amplifies the score. SwStr% — the penalty. The upstream cause of strikeouts, not the downstream outcome. Captures the moment of failure — the swing that misses entirely — before it shows in the box score.
The Normalization — Why T-Score: Most normalized metrics use min-max scaling — take the best player, call them 100, take the worst, call them 0. This has a critical flaw: the meaning of every score shifts as the player pool changes. One freakish outlier at the top compresses every other player toward the bottom. PIIS-T uses T-Score normalization — the same statistical framework used in sports science, psychometrics, and academic standardized testing. Formula: z = (Raw PIIS − μ_level) / σ_level, then PIIS-T = (z × 10) + 50, clamped 0–100. μ_level and σ_level are the mean and standard deviation of all qualifying players at that specific level. Result: 50 is always exactly league average — permanently anchored, not relative to the current filter or leaderboard view. Every 10 points equals exactly one standard deviation. Approximately 68% of qualifying players will score between 40 and 60. Fewer than 2.5% will exceed 70. A 75+ PIIS-T is not a hot streak. It is a demonstrated elite process. This is the first application of T-Score normalization to a composite MiLB hitting process metric across all four full-season levels.
Analytical Foundation: PIIS-T combines four independently validated process metrics using a statistically rigorous normalization framework standard in sports science. Each component has documented predictive validity in published sabermetric research — Z-Contact% and SwStr% stability work documented by Ben-Porat (The Hardball Times, 2018) and Tango, Lichtman, and Dolphin (The Book, 2006); BB% and discipline metric stability established across multiple peer-reviewed studies. PIIS-T is a novel application of these components to MiLB data at scale. It is the first metric to combine contact execution, plate discipline, power sustainability, and swing efficiency into a single T-Score normalized number available at all four full-season MiLB levels. Formal validation against promotion timelines and future wOBA outcomes is ongoing as our dataset grows through the 2026 season and beyond.
The Four Scenarios — How to Use PIIS-T:
PIIS-T 65+ and wRC+ 130+ — The Real Deal. Process confirms outcomes. Elite fundamentals backing elite results. Trust the performance — it is backed by a demonstrated process. These are players you build around in dynasty. They are not regression candidates. They are promotion candidates.
PIIS-T 65+ and wRC+ under 115 — Diamond in the Rough. The most valuable signal in PitchIQ. Elite process, suppressed results. This divergence has identifiable causes: BABIP bad luck, pitcher-friendly park suppressing counting stats, small result sample, or a hitter making all the right decisions without receiving pitches to drive yet. Buy low before the industry catches on. Positive regression is a mathematical expectation, not a hope. Specifically look for: Z-Contact% 82%+, BB% 12%+, dampened ISO .150+, SwStr% under 9% combined with wRC+ under 115. When those align you have found a future breakout.
wRC+ 130+ and PIIS-T under 35 — Regression Candidate. The most dangerous profile in dynasty. Production not supported by process. Likely driven by BABIP luck, a hot streak on a small sample, favorable park, or weak opponent quality. Sell high before the results collapse. SwStr% is too high, BB% too low, or ISO propped by a few hard-hit balls in a compressed window. When pitchers adjust and attack the weaknesses PIIS-T has already flagged, the box score will crater. Red flags: wRC+ 130+ with PIIS-T under 35, SwStr% above 14%, BB% under 6%, Z-Contact% under 70%.
PIIS-T under 35 and wRC+ under 100 — Context Required. Not all low-PIIS-T players are sells. An 18-year-old IFA at Low-A with PIIS-T 30 in 50 PA is still adjusting to professional pitching — expected and unremarkable. A 24-year-old at Double-A with PIIS-T 30 in 350 PA is a significant red flag. Age relative to level changes everything. Cross-reference with MLB Probability, DVS, and the age context banner. No single metric tells the whole story. PIIS-T tells the process story. The other metrics tell the ceiling story. Together they give you the truth.
Tiers: 75–100 = Elite (top 2.5%, 2+ SD above average) · 65–74 = Plus (top 7%, 1.5 SD above) · 55–64 = Above Average (top 30%) · 45–54 = Average (within 0.5 SD of mean) · 35–44 = Below Average · 0–34 = Poor (1.5+ SD below average)
Transparency: Every PIIS-T component is visible in PitchIQ — Z-Contact%, BB%, ISO, and SwStr% are all displayed in the leaderboard and player cards. The formula is published. The normalization method is fully explained. The guardrails — 40 PA minimum, ISO dampener, O-Swing% floor at AA/High-A — are documented here. PIIS-T is a tool, not a verdict. Use it alongside wRC+, DVS, MLB Probability, and age context for the complete picture. ProspectTilt believes that analytical transparency builds better analysts.
wRC+ (MiLB) is a park-adjusted, league-adjusted weighted runs created metric calculated directly from PitchIQ plate appearance data. A score of 100 means exactly league average for that level. Above 100 is above average, below 100 is below average.
Formula: Player wOBA is calculated from actual outcomes (BB, HBP, 1B, 2B, 3B, HR) using standard 2026 wOBA weights. Park adjustment uses the half-park-factor method: park_adj_wOBA = raw_wOBA / ((PF + 100) / 200). League wOBA (lgwOBA) is derived from all plate appearances in PitchIQ at that level. wRC+ = ((park_adj_wOBA − lgwOBA) / wOBA_scale + lgR/PA) / lgR/PA × 100.
Why it differs from FanGraphs: FanGraphs wRC+ anchors lgwOBA to the MLB run environment (~0.310–0.320), then scales down. PitchIQ wRC+ uses the actual MiLB run environment derived from our database (~0.330–0.340 depending on level). This makes PitchIQ wRC+ a true within-level comparison — 120 means 20% above Double-A average. FanGraphs wRC+ is MLB-scaled, so the same player will show a lower number there. Neither is wrong — they measure different things. PitchIQ wRC+ is more accurate for comparing prospects to their peers at the same level.
Park factors: Source is Baseball America 2024 MiLB Park Factors (Matt Eddy, January 2026). wOBA park factor used as primary metric. Half-adjustment applied since players split games between home and away.
Update frequency: Recalculated nightly as part of the enrichment pipeline. Reflects all plate appearances in the current season to date.
