vyndr/specs/runs-rbi-per-archetype.md

runs + RBI — mostly-base-rate confirmed, and stronger than expected

Nothing proved. For RBI even the ARCHETYPE split is theatre, so the honest grade is the POOLED base rate. The order anticipated that mostly-base-rate would be the correct answer for context-heavy stats. It is, and one level deeper than predicted.

Premise note

The order's closing line says the batter board is "per-archetype-graded" after this. It is not: nothing has been rescaled for hits or total_bases either — no archetype slot has ever reached sample, and gradeBands remains built, gated and unwired. This is the fourth stat measured, not the completion of three.

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STEP 1 — Full-history audit

	clean	with p_win	players	dates	games	lines
RBI	935	931	344	5	43	0.5 on 885
RUNS	617	614	334	5	33	0.5 on all

Zero quarantined in either. No archetype slot reaches 500.

archetype	RBI n	RUNS n
UNLABELLED	546	341
BOMBER	207	148
GHOST	92	67
BRUSH	43	26
DRIVER	24	20
CATALYST	13	9

The signature archetypes the order names are the two smallest slots on the board — RBI→DRIVER at n=24, runs→CATALYST at n=9. The hypothesis is reasonable and we are three orders of magnitude from being able to test it.

RUNS is refused structurally before any factor is tested: 33 game clusters against a 40 floor. Reported as such rather than dressed up as a factor result.

Inputs reconstructed rather than declared missing

lineup_context only covers 2026-08-04/05/06 (ingest began last week) while settled rows start 07-31, so just 187 of 617 runs rows join to a batting order. That reads as input-blocked — but the play-by-play cache runs from 05-01, and the batting order IS the order batters first appear. Batting slot, power behind (mean barrel of the next three slots) and reach-base rate were all reconstructed point-in-time from it: coverage went 187 → 574.

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STEP 2/3 — The gate (153 / 168 cumulative tests)

RBI — all THEATER

factor	n	clusters	shift	Brier Δ	CI	verdict
risp_opportunity	803	43	0.0585	+0.0047	[−0.0023, +0.0122]	THEATER
extra_base_skill	881	43	0.0271	+0.0010	[−0.0023, +0.0042]	THEATER
risp × extra_base	803	43	0.0624	+0.0056	[−0.0042, +0.0135]	THEATER

RUNS — all refused on cluster count, all pointing the wrong way

factor	n	clusters	shift	Brier Δ	verdict
reach_base	525	32	0.0383	+0.0043	PENDING — k<40
lineup_power_behind	574	32	0.0232	+0.0008	PENDING — k<40
reach × power_behind	525	32	0.0482	+0.0054	PENDING — k<40

The compound is the WORST version, in both stats

RBI: 0.0047 / 0.0010 → 0.0056 compounded. RUNS: 0.0043 / 0.0008 → 0.0054 compounded.

The causally-correct compound was the most promising factor on the sheet and is the most harmful in both. Two multipliers that individually carry nothing do not cancel — they compound each other's noise. Related to but distinct from the collapsed-sequence lesson: there the product of two REAL effects was too small to use; here the product of two NULL effects is actively worse than either.

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The archetype itself does not rescue it

The archetype base rates look strongly differentiated, and that appearance is most of the trap:

	RBI	RUNS
DRIVER	0.609 (n=23)	0.500 (n=20)
GHOST	0.467	0.716 (n=67)
BOMBER	0.413	0.460
pooled	0.4305	0.5721

Tested directly — is the archetype's leave-one-out base rate better than the pooled one?

	shift	Brier Δ	CI	verdict
RBI	0.0231	+0.0010	[−0.0034, +0.0050]	THEATER
RUNS	0.0642	−0.0028	[−0.0147, +0.0108]	CANDIDATE — k=33

For RBI, knowing the archetype makes the forecast worse. DRIVER's 0.609 is n=23 — the spread is small-slot noise wearing a decimal point. Runs is at least directionally favourable, and unproven.

Had this been read off the base-rate table instead of gated, the session would have shipped "archetype differentiation is real and large" as a finding. It is not one.

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The cross-stat pattern that IS real

stat	mean p_win	actual	counter bias
total_bases	0.5698	0.5074	+0.0624
RBI	0.4860	0.4313	+0.0547
runs	0.5949	0.5749	+0.0200

The counter over-predicts every batter counting stat measured. Across four stats and three sessions, calibration is the systematic defect and factor scarcity is not — TB's held-out isotonic fix (−0.0039 Brier) still outperforms every factor tried on any stat, all of which have been null or theatre.

STEP 4 — No rescale

Two-bar rule: nothing proved, nothing certified calibrated, no slot at sample — and for RBI the archetype split is itself theatre, so the honest band is the POOLED base rate rather than a per-archetype one. gradeBands returns exactly that by construction.

Next, by value

1. Calibrate the counter across all four stats. One systematic bias, measured four times, larger than anything else on the board.
2. Stop adding factors to context stats. Six tested across runs/RBI, six null-or-worse, and the compounds worst of all.
3. Runs needs game-date accrual to clear the cluster floor before it can be gated at all.

Counter and frozen clusters byte-identical.