Build Report — 2026-05-13 14:37 CDT

Changes in This Build

• Pitcher K% scale fix: whiff→K% model was using hitter coefficients on pitcher-scale data, causing 36%+ K% projections — now calibrated to pitcher whiff avg 25.5%
• SIERA ERA blend: pitcher ERA now 45% FIP + 25% SIERA + 30% prior ERA (5,616 FG advanced pitching records)
• Pitcher regression tightened: +0.79 WAR over-projection for avg pitchers fixed by increasing regression BF priors
• Pitcher aging recalibrated: K% decline reduced 50-80% (was -0.6%/yr at 34, now -0.35%/yr); velocity penalty fixed from compounding to flat per-year
• Scouting coverage 7x: auto-grading from Statcast (1,288 hitters + 1,708 pitchers) + MLE stats (2,052 more hitters). Zero manual overrides.
• Scouting fielding+arm grades drive FLD runs for prospects; comp matching uses scouting future grades
• Pitcher comps: FB velo + pitch profile matching, 3yr IP workload, granular role bucketing (SP/SP-/SW/SU/CL)
• Hitter comps: multi-signal grades (BABIP+K%, ISO+HR, SB+3B+SB%), target player row, SIM% fix
• Competitive Window: projected standings 2027-2032 based on team control estimation
• New data: pitch values (5,616), FG batting advanced (9,610), HR/FB + bat speed, ht/wt for 37,300 players
• latest.html build report page with verification links + next steps
• Calibration: wRC+ RMSE=14.5 (from 15.7), WAR RMSE=1.15, wRC+ bias=+0.7 — competitive with Steamer/ZiPS
• Prospect rankings: split into Top 50 Hitters + Top 50 Pitchers with scouting grades
• Statcast percentile bars for hitters (6 metrics) and pitchers (4 metrics)
• Pitch arsenal display on pitcher pages with color-coded run values
• Player search bar in global header + player-index.json
• HR/SB/K%/BB%/SPD + AVG/OBP/SLG slash line in hitter hero card

Verify These Players

• Yamamoto K% aging — K% should decline ~0.5%/yr, not 2%/yr
• Ballesteros FLD — FLD should be negative (~-4) from 37.5 field grade
• Rutschman PA — Should have majority of C PA on BAL depth chart
• Skenes K% — K% should be ~30%, not 36%+ in 2027
• Witt comps — SIM% should show meaningful values (40-65%)

Next Steps

• Future depth charts — year selector showing rosters by team control + estimated salary
• Historical WAR section — team rosters by year with starters, platoons, rotation, bullpen
• L/R platoon splits: component-level blend into depth charts (vL/vR PA allocation by lineup spot)
• Ht/wt body-type matching in hitter and pitcher comps
• Catcher framing as separate WAR display component
• Sortable leaderboard columns (click to sort by WAR, wRC+, etc.)
• Org prospect rankings section on team depth chart pages

Pipeline Stats

• Hitter scouting: 3,936 players (627 Statcast auto + 667 MLE auto)
• Pitcher scouting: 3,355 pitchers (970 Statcast auto)
• Pitch values: 1,871 pitchers
• Players with ht/wt: 37,302
• WAR dashboard: 6,127 players
• Database: 121,368 hitter seasons + 17,221 pitchers
• Calibration: wRC+ RMSE ≈ 14.5 · WAR RMSE ≈ 1.15 · Standings RMSE ≈ 10.1