The receipts · published verbatim from the working file
H5 component stability
The gating test — includes the clutch null result (yoy r = 0.043) and the pitcher-signal caveats that keep arms uncalled.
H5 Component Stability — v0 results (2026-07-11)
First run of the backtest's gating hypothesis: year-over-year stability (same player qualified in consecutive seasons, 2015-2025, 2,377 batter pairs / 2,319 pitcher pairs). Spec rule: Pearson r < 0.35 in Tier 1 → component weight halved and reclassified as a volatility driver (legitimate for story/repricing, never marketed as predictive skill).
Results (rate-normalized; excluding 2020-adjacent pairs shown in
parentheses — direction unchanged)
| Component (v0 estimator) | Pearson r | Verdict |
|---|---|---|
| pitches/PA (grind core) | 0.737 (0.745) | STRONG skill — most stable thing measured |
| hi-leverage BB rate (grind/discipline) | 0.427 (0.433) | Skill |
| RE24 per PA (situational offense) | 0.398 (0.419) | Skill, modest |
| Pitcher FIP-core (run prevention) | 0.366 | Skill, just clears bar (matches published FIP YoY) |
| WPA per PA | 0.248 (0.263) | VOLATILITY (below 0.35) |
| XBT rate (baserunning v0) | 0.202 (0.212) | Below bar — see caveat 2 |
| Clutch per PA (in-house variant) | 0.043 (0.060) | ~ZERO. Not a skill. |
| Pitcher leverage per IP | 0.055 | Role/context-driven, volatility |
Interpretation
- "Clutch is not a skill" reproduced exactly (r = 0.04 across 2,377 pairs) — consistent with decades of sabermetric research on FanGraphs' Clutch stat. Per the spec's volatility-component doctrine: the Clutch weight (15% in the v1.0 hand-set vector) is halved and the component is reclassified as a volatility/story driver. It remains great CONTENT (nightly narrative, repricing texture) and must never be marketed as predictive.
- XBT-rate caveat: published baserunning value (BsR-style) shows moderate YoY stability (~0.4-0.5); our r = 0.20 likely reflects a noisy v0 estimator (small opportunity counts, no empirical-Bayes shrinkage, no pickoff/steal inputs) rather than "baserunning is not a skill." Action: improve the estimator (shrinkage + steal components from runner_moves) BEFORE judging the component.
- The grind thesis survives its first contact with data. The formula's largest weight (30%) rests on the most stable measured input. High-leverage BB rate also clears the bar.
- Prefer RE24-family inputs over WPA-family inputs in the predictive variant; WPA belongs to the volatility/story layer.
Caveats
- v0 estimators only: no defense component yet (TZ estimate pending), no starter-exit contribution, park adjustment missing from FIP-core, WE table has known refinements pending (ghost-runner era split for extra innings; FanGraphs comparison pass not yet run).
- Qualification: PA >= 200 / outs >= 120; 2020 not pro-rated (2020- adjacent pairs excluded in the sensitivity column; direction unchanged).
- These correlations gate the H5-ADJUSTED weight vector; per spec, H1/H2 run with BOTH the hand-set and adjusted vectors.
Content note (bank)
"We measured clutch across 2,377 player-season pairs and it isn't a skill — here's the whole methodology" is a strong first FanGraphs-Community-Blog / r/Sabermetrics credibility piece for the probe's week-1 sequence (v2 brief §8): pure research, no product, peer-reviewable, and it establishes the miss-inclusive honesty brand before the first call is ever published.