The causal insight is right -- the game is a sequence and the matchup does
shift mid-game. The direction is backwards, measured on 93,663 plate
appearances from 1,238 games pulled free from statsapi.
LINK 1 PROVES. Starter batters-faced, point-in-time from his own prior
starts only, clustered on the pitcher: MAE 3.2226 -> 2.7990, delta
-0.4236, CI [-0.6006,-0.2731] at 0.9995 corrected for 107 tests, 1,706
starts across 204 pitchers. It finds the tail the chain needed -- early
exits are a 23.2% base rate, model-flagged starts are 34.0% early, lift
+10.8pp.
Scope correction inside Link 1: the order specifies fatigue x GAME
SCRIPT, but game script is not available at grade time -- whether he gets
hit tonight is the thing being projected, not an input to it. Only the
workload half is measured; the in-game half is recorded as a live feature,
out of scope, rather than quietly folded in.
LINK 2 DOES NOT PROVE, twice over. Model accuracy 17.2% vs an 8.6%
baseline -- doubling it sounds good and is not, since naming a specific
arm is wrong five times in six. And structurally the entity is the
BULLPEN: 39,629 post-starter plate appearances across 30 clubs is 30
readings, below the 40-cluster floor, the same permanent ceiling as park
geometry and team defence. LINK 3 NOT RUN, per the order's own rule.
THE PREMISE IS REFUTED, and this chains on nothing so it was safe to
measure:
vs STARTER n=48,492 hit rate 0.2444 +/-0.0038
vs BULLPEN n=35,760 hit rate 0.2373 +/-0.0044
The pen is 0.7pp HARDER. The specific effect the chain exists to exploit
-- early exit making later at-bats softer -- is +0.0010 on 35,760 PAs. A
well-powered null, not a sample problem.
What IS real is times through the order: TTO1 0.2351 -> TTO2 0.2515 ->
TTO3 0.2518. A starter does decay as the lineup sees him again, but that
advantage is SURRENDERED when he leaves, not extended -- the pen is
harder than his second and third time through. A modern bullpen is a
queue of fresh specialists throwing one inning each; there is no tiring
arm to punish.
So the insight survives inverted, and Link 1 stays valuable for the
opposite reason it was built: a likely early hook predicts the hitter
LOSES his third-time-through look (0.2518 -> 0.2373 on that PA). The
mispricing is on hitters who get an EXTRA look at a starter going deep.
BUILT: predictionGate.js + tests -- the two-part gate for a continuous
prediction. factorGate binarises outcomes for Brier, which would destroy
a target like batters faced. Same discipline, same THEATER verdict, real
scale.
PRE-REGISTERED NOT RUN: Link 2' using a PA-weighted bullpen AGGREGATE
rather than a named arm. Recorded rather than substituted in -- running
Link 3 on a swapped-in Link 2 is the assumed-link failure the order
forbids. Given the premise result its expected value is now low.
PARALLEL TRACK logged: total_bases n=948 pooled, BOMBER x TB 340, short
by 160. Sample-readiness only, not a verdict.
Counter and frozen clusters byte-identical.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01W1sivYNqY2TS5ftykmHBU9
builtbykev
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