builtbykev
aa1228ec42
Firing verified on a real prod snapshot: 10/10 total_bases props carry proj_tb_p_over. The snapshot HTTP call returned 524 (Cloudflare's 100s origin timeout vs a ~115s snapshot) but the work completed server-side -- confirmed from the ledger rather than assumed. Face validity is good and diagnostic: means agree almost exactly with the ladder (1.813 vs 1.833), so this is a SHAPE-ONLY intervention, which is what was intended. Component rates are plausible, and Carroll's triples rate (0.112, far above his peers) is a clean check -- he is a speed player and the model sees it. AN OBSERVATION I AM NOT RESOLVING BY EYE: tb-v1 reads systematically LOWER than the ladder (0.424 vs 0.540 at the same mean). That is the expected DIRECTION, since the NB overstates P(>=2) by treating a home run as four accumulating events -- but whether 0.424 is right or an overcorrection is not knowable from face validity. A ~1.8-TB hitter clearing 1.5 empirically sits nearer 45-50%, between the two. I am not claiming tb-v1 is better; the holdout decides. BRANCH PRE-REGISTERED, before the result, so the verdict cannot be reinterpreted afterward: improves -> family-mismatch HOLDS, similarity stays off the critical path, hits is next; does not improve -> hypothesis WRONG and the mean-weakness/similarity branch REOPENS. Also recorded: I hit Number(null)===0 in my own new module -- a null component rate treated as a measured zero, the difference between "never triples" and "we don't know his triple rate". A test caught it. Sixth appearance of this trap in this codebase, and it caught the person writing the warnings about it. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01QJs13VsyiSKYQP6rj3NNmc
140 lines
5.3 KiB
Markdown
140 lines
5.3 KiB
Markdown
# tb-v1 — TOTAL BASES AS A COMPOUND OUTCOME (challenger)
|
||
|
||
**Date:** 2026-08-02 · current ladder + champion `p_win` **byte-identical** ·
|
||
ledger-only · **firing verified on a real prod snapshot**.
|
||
|
||
**Gates:** 4,104 tests / 329 suites green · `next build` exit 0 · tb-v1 on
|
||
**10/10 total_bases props** · holdout committed, verdict n-blocked.
|
||
|
||
---
|
||
|
||
## STEP 0 — COMPONENTS CONFIRMED ON REAL DATA
|
||
|
||
statsapi has **no `singles` field**. But on a real 10-game log:
|
||
|
||
```
|
||
singles = hits − doubles − triples − homeRuns
|
||
singles + 2·doubles + 3·triples + 4·homeRuns == stored totalBases ✓ exact
|
||
```
|
||
|
||
**The decomposition is exact, not an approximation.** Verified before any code
|
||
was written — this fix depended on it.
|
||
|
||
---
|
||
|
||
## THE MODEL
|
||
|
||
Each component gets its own per-game Poisson rate; TB is their weighted sum, and
|
||
the PMF is built by **exact convolution** rather than simulated (TB support is
|
||
small). It inherits the **same combined multiplier** proj-v1.1 computes, so the
|
||
two models differ **only in structure**.
|
||
|
||
### Why this is the fix, in one number
|
||
|
||
With **identical mean TB of 1.0**:
|
||
|
||
| hitter | P(TB≥2) | **P(TB≥4)** |
|
||
|---|---:|---:|
|
||
| pure home-run hitter | 0.221 | **0.221** |
|
||
| pure singles hitter | 0.264 | **0.019** |
|
||
|
||
**A 12× difference at the 4-base rung that an NB on TB alone cannot express**,
|
||
because it treats one home run as four independent events. A test asserts this
|
||
separation, and asserts that P(TB≥4) for a pure-HR hitter equals P(at least one
|
||
HR) **exactly**.
|
||
|
||
### The approximation, stated
|
||
|
||
Components are modelled as **independent** Poissons. They are not: a plate
|
||
appearance that becomes a double cannot also become a single, so they are weakly
|
||
negatively correlated and **independence slightly overstates the tail**. Closer
|
||
to the truth than what it replaces; **not a solved problem**, and labelled
|
||
`independence_caveat: true` on every record.
|
||
|
||
---
|
||
|
||
## FIRING ON PROD — 10/10 TB PROPS
|
||
|
||
| | |
|
||
|---|---:|
|
||
| rows written | 241 |
|
||
| total_bases props | 10 |
|
||
| **with `proj_tb_p_over`** | **10 (100%)** |
|
||
| range / sd | 0.295–0.424 / 0.045 |
|
||
|
||
Real records:
|
||
|
||
| player | line | ladder mean | **ladder P** | **tb-v1 P** | tb-v1 mean | rates (1B/2B/3B/HR) | games |
|
||
|---|---:|---:|---:|---:|---:|---|---:|
|
||
| Ketel Marte | 1.5 | 1.813 | **0.540** | **0.424** | 1.833 | .614/.208/.028/.180 | 106 |
|
||
| Corbin Carroll | 1.5 | 1.814 | 0.540 | 0.424 | 1.815 | .468/.206/**.112**/.150 | 107 |
|
||
| Gabriel Moreno | 1.5 | 1.590 | 0.471 | 0.405 | 1.608 | .773/.221/.000/.098 | 84 |
|
||
|
||
**The means agree almost exactly** (1.813 vs 1.833) — both use the same rate
|
||
machinery. **Only the shape differs**, which is precisely the intended
|
||
intervention. Carroll's triples rate (0.112, far above the others) is a good
|
||
face-validity check: he is a speed player, and the model sees it.
|
||
|
||
### An observation the holdout must settle
|
||
|
||
**tb-v1 is systematically LOWER than the ladder** (0.424 vs 0.540 at the same
|
||
mean). That is the expected *direction* — the NB overstates P(≥2) by treating a
|
||
home run as four accumulating events. But **whether 0.424 is right, or an
|
||
overcorrection, is not knowable from face validity.** A ~1.8-TB hitter clearing
|
||
1.5 empirically sits nearer 45–50%, which is between the two.
|
||
|
||
**I am not claiming tb-v1 is better. The holdout decides.**
|
||
|
||
---
|
||
|
||
## HOLDOUT — COMMITTED, VERDICT n-BLOCKED
|
||
|
||
`scripts/tb-compound-holdout.sql`, with two guards baked in:
|
||
|
||
1. **TB rows ONLY.** total_bases is 49 of 437 settled rows; averaging into other
|
||
stats would hide the effect entirely.
|
||
2. **DIRECTION-ALIGNED.** `p_win` is P(graded side); both projection values are
|
||
P(over). 31.4% of rows are under-graded, and the unaligned comparison is the
|
||
artifact that accounted for **41%** of the ladder's apparent loss.
|
||
|
||
**Settled TB rows carrying tb-v1: 0** — it went live today, on games not yet
|
||
played. First settle pass is tomorrow.
|
||
|
||
---
|
||
|
||
## THE DIAGNOSIS IS ON TRIAL — recorded in advance
|
||
|
||
> **If tb-v1 materially improves TB resolution** → the family-mismatch hypothesis
|
||
> **HOLDS**, similarity stays **off** the critical path, and **`hits` is next**
|
||
> (its own order: AB-bounded, mostly 0.5 lines, so it rides on P(0)).
|
||
>
|
||
> **If it does NOT improve** → the hypothesis is **WRONG**, and the
|
||
> **mean-weakness / MLB-similarity branch REOPENS**.
|
||
|
||
Written down now, before the result, so the verdict cannot be reinterpreted after
|
||
the fact.
|
||
|
||
---
|
||
|
||
## A TRAP I HIT IN MY OWN CODE
|
||
|
||
`Number(null) === 0` — again, and this time in the new module. A null component
|
||
rate passed a naive finite check and was treated as a **measured zero**. That is
|
||
the difference between *"this player never triples"* and *"we do not know his
|
||
triple rate"*, and it would have silently narrowed the distribution.
|
||
|
||
**A test caught it.** Both `tbPmf` and `tbMean` now reject `null`/`''`/boolean
|
||
strictly. Recording it because this is the sixth time this specific trap has
|
||
appeared in this codebase, and it caught the person who has been writing the
|
||
warnings about it.
|
||
|
||
## TAGS
|
||
|
||
**VERIFIED:** the TB decomposition is exact on real logs · tb-v1 fires on 10/10 TB
|
||
props · means agree with the ladder (shape-only intervention) · component rates
|
||
face-valid (Carroll's triples) · 12× separation at the 4-base rung.
|
||
|
||
**NOT CLAIMED:** that tb-v1 is better. n-blocked until TB rows settle.
|
||
|
||
**STATED LIMITATION:** component independence overstates the tail.
|