What Goes Into PSI+
Weighted valid whiffs divided by weighted eligible pitches across the full eligible arsenal. Two-strike pitches count double, first pitches count half, and all other pitches receive neutral weight.
CLW is not fastball-only. Every eligible pitch contributes to the weighted rate.
Captures the upper-end fastball speed a pitcher can reach. It uses the 95th percentile instead of an average or a single maximum.
95th percentile of release speed across four-seam fastballs, sinkers, and cutters. This measures a pitcher’s top-end gear without letting one isolated reading define the component.
Measures how flat or steep a fastball enters the plate. PSI+ uses the raw average VAA of four-seam fastballs, sinkers, and cutters.
Raw average vertical approach angle at the front of home plate for FF, SI, and FC. More negative values indicate a flatter plane. The measure is not adjusted for pitch location.
Applies the same count-weighting logic as CLW to eligible secondary pitches. Those whiffs already appear in CLW, so SLWR gives that subset additional emphasis.
Applies count-leverage multipliers to breaking balls, changeups, and other eligible off-speed pitches. It is included after a pitcher reaches 50 eligible secondary pitches.
2026 Season-to-Date Leaderboard
Current-season production scores with a minimum of 200 eligible pitches. Starters and relievers are normalized separately. A 100 is the mean for the relevant season and role, 110 is about one standard deviation above it, and 120 is about two.
Rolling PSI+ Over Time
This is not the season-to-date leaderboard. Each point uses the pitcher’s previous 1,000 eligible pitches, requires at least 200, and excludes the current appearance.
When PSI+ and K% Saw Different Profiles
These examples illustrate what a disagreement can look like. They are not part of the 2025 validation evidence.
Luzardo’s current four-component historical score is 114.6. Wainwright’s is 78.5. Both use the same four-component identity as current production PSI+.
What the 2025 Test Showed
The exact production weights had already been informed by 2025, so they are not presented as a clean 2025 holdout. The public results below come from a four-component reconstruction whose rules and weights were selected using only 2020–2024 information, then evaluated on 2025. It is a validation construction, not a second live PSI+ metric.
At the 0.5 SD threshold, the direction was above 50% in the 2024 to 2025 held-out test, but incremental lift over ordinary regression remained uncertain. The 1 SD result was stronger, but only 18 cases cleared that bar. This is one held-out outcome-season pair.
How the Formula Reached Four Components
PSI+ originally began with CLW, fastball velocity ceiling, and VAA at 60%, 30%, and 10%. That construction leaned too heavily on fastball traits, so SLWR was added to give secondary-pitch swing-and-miss more representation.
Production and Validation Boundaries
Production PSI+ is the season-and-role normalized 55/35/5/5 score used on the live leaderboard. The clean reconstruction exists only to evaluate the four-component idea on 2025.
A score of 100 is the mean for the relevant season and role population. A 110 is about one standard deviation above that mean, and a 120 is about two. PSI+ points are standardized distances, not percentages above average.