STEP 1 -- input mapped and measured. opportunity_drift 94% coverage on 100
real props: 100% for batters (total_bases, hits, home_runs), 40-67% for
pitchers, which is correct -- pitchers accumulate few at-bats so the ratio
is genuinely undefined and ABSTAINS rather than being invented.
STEP 2 -- THE COLLINEARITY GUARD PASSES DECISIVELY. Pearson r on n=94:
drift vs l20_avg -0.020, vs l5_avg +0.027, vs ab_per_game -0.029. All
essentially zero, so the axis is orthogonal to every existing projection
input and carries information the projection does not already contain.
That also validates the ratio-over-level decision EMPIRICALLY: ab_per_game
is the same quantity over the same denominator as l20_avg, so the level
would have been redundant. Dividing by the player's own baseline removed
the collinearity -- r = -0.029 against the very quantity it is built from.
STEP 3 -- live as a challenger, verified on prod over an induced 416-grade
snapshot: 142 of 276 rows (51.4%) carry the opportunity axis, the
challenger moved on 190 rows, mean |delta| 0.034, range -0.089..+0.108.
Champion p_win and the live grade path are unchanged.
STEP 4 -- HOLDOUT IS n-BLOCKED BY CONSTRUCTION and I am not manufacturing
one. Settled rows carrying the axis: 0. Its first rows carry game_date
2026-08-01 -- games that have not been played. Running the test on rows the
axis never touched would dilute the comparison with rows where challenger
=== champion by construction, making a null result look like a small
positive one. Query committed for when n arrives; it filters to
axis-carrying rows for exactly that reason, buckets before measuring
reliability, and splits time-forward. BOTH metrics must improve or the axis
is shelved.
A MEASUREMENT TRAP RECORDED: the first prod run showed drift at 0% while
ab_per_game read 94% -- indistinguishable from "the feature does not
compute". It was the 120-second feature-vector cache serving payloads
written by the previous image. A new feature field is invisible for one
cache generation after deploy. I nearly reported it absent, having already
confirmed atBats is present in the live statsapi payload and that the code
produced drift = 1.05 locally on that exact data; the contradiction
between those two facts is what saved it.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QJs13VsyiSKYQP6rj3NNmc
builtbykev
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