# TOTAL BASES — solo baseline, interactions, and the validity blocker

**2026-08-03.** Challenger-only. Counter byte-identical (zero diff on
`probabilityEstimator.js` / `analyzeViaEngine1.js`).

> **HEADLINE 1 — nothing can be gate-validated today, and the reason is my own
> fix.** `statcast_aggregates` is upserted in place and keeps **one as-of date**.
> The first skill backtest was honest only by accident: the nightly refresh was
> unreachable code, so profiles sat frozen at 2026-07-21 — *before* the settled
> window. Repairing that cron (correct for production) refreshed them to today
> and destroyed every prior version. **Point-in-time validation is now
> structurally impossible from that table**, so every number below is
> **contaminated / directional** and none is a gate verdict.
>
> **HEADLINE 2 — on total bases the skill model is at PARITY with the counter**
> (0.2718 vs 0.2647, CI includes zero). On hits it lost by 0.116 with a CI
> excluding zero. Same engine, same day. **The stat choice was the whole story.**

---

## 0. Premise correction

The order states "barrel rate PASSED, exit velo/launch/matchup FAILED solo."
**Nothing passed.** Yesterday's run refused *every* TB feature on
`insufficient_data` (n=295 < 500); barrel rate's marginal r was 0.088 and the
strongest was hard-hit at 0.153. Today at n=383, **hard-hit has fallen to
0.135** — see §3, because that drift is itself the most informative number here.

## 1. The validity blocker, and the fix

```
select updated_at::date, count(*) from statcast_aggregates group by 1;
→ 2026-08-03 | 1387        ← ONE row. No history. 2026-07-21 is gone.
```

A season aggregate dated 2026-08-03 used to score a 2026-07-25 game **contains
that game**. That is leakage, and it is not repairable after the fact.

**Fixed forward:** `statcast_history` (migration applied) retains a dated
snapshot on every refresh, keyed `(as_of_date, sport, season, source_id, role)`.
Point-in-time becomes `where as_of_date < game_date order by as_of_date desc
limit 1` — the profile as it stood *before* the game, by construction. Retention
is best-effort and **cannot fail the refresh**; both properties are unit-tested.
It has one day of data, which is not yet a window.

## 2. Feature → conditioning variable → mechanism (STEP 2)

| interaction | conditioning on | mechanism |
|---|---|---|
| `launch × exit_velo` | each other | Extra bases need **both**: hit hard AND in the air. A 105-mph ground ball is an out; a 25° popup is an out. Neither predicts alone — which is exactly why each can fail solo and the product might not. |
| `exit_velo × pitcher_hard_hit_allowed` | pitcher suppression | A hitter only realises contact quality against a pitcher who permits it. Elite suppression attenuates a power bat; a contact-permitting arm amplifies it. Conditional by construction. |
| `barrel × power archetype` | **real archetype label** | Barrels convert to extra bases for hitters whose lane is power. This is Discipline 2 as a testable claim. |
| `batter_K × pitcher_K` | each other | Strikeout risk compounds (log5 is this shape). A PA lost to a strikeout is a base opportunity that never happens — suppression through **opportunity**, not contact. |
| `pull_rate × park` | park | **UNTESTABLE** — park is passed as 1.0 everywhere and pull rate is not ingested. |

## 3. STEP 1 — solo baseline (the control)

n=383, Bonferroni across 12 tests → corrected α = **0.00417**.
The decider is correlation with the **counter's residual** (`won − p_win`) — a
feature correlating with the raw outcome may simply know what the counter
already knows.

| feature | r vs outcome | **r vs residual** | p | would it pass at n≥500? |
|---|---|---|---|---|
| **batter_hard_hit_pct** | 0.172 | **0.135** | 0.0080 | **No** — |r| < 0.15 *and* p > 0.00417 |
| batter_exit_velo | 0.120 | 0.070 | 0.173 | No |
| batter_barrel_pct | 0.109 | 0.078 | 0.127 | No |
| pitcher_k_pct | −0.094 | −0.087 | 0.093 | No |
| batter_launch_angle | 0.032 | 0.003 | 0.948 | No |
| batter_bb_pct | −0.019 | −0.026 | 0.607 | No |
| pitcher_hard_hit_allowed | 0.024 | 0.035 | 0.501 | No |
| batter_k_pct | −0.009 | −0.003 | 0.952 | No |

**No feature passes solo, and hard-hit is drifting the wrong way.** Its marginal
r went **0.153 (n=295) → 0.135 (n=383)** as sample grew. That is the signature of
an estimate regressing toward its true value as noise averages out, not of a real
effect firming up. Yesterday I called it "the most encouraging number this work
has produced"; on 88 more rows it is fading. **Worth stating plainly, because the
temptation is to keep quoting the older, better number.**

## 4. STEP 3 — interactions, each against its own parts

Incremental signal = partial correlation of the interaction with the residual,
**controlling for both components**. If an interaction is barrel rate in a hat,
regressing out barrel rate collapses it.

| interaction | n | raw r | best component r | **incremental r** | verdict |
|---|---|---|---|---|---|
| `barrel × power archetype` | 260 | −0.046 | 0.019 | **−0.101** | UNDERPOWERED — n below gate |
| `launch × exit_velo` | 383 | 0.007 | 0.070 | −0.053 | UNDERPOWERED |
| `batter_K × pitcher_K` | 378 | −0.050 | 0.087 | −0.024 | UNDERPOWERED |
| `exit_velo × pitcher_suppression` | 378 | 0.048 | 0.073 | 0.013 | UNDERPOWERED |

Only the archetype interaction has an incremental exceeding its parts (0.101 vs
0.019) — the shape Discipline 2 predicts — but at n=260, with a negative sign,
and nowhere near the gate. **It is a lead, not a finding.**

### A methodological catch worth recording

The archetype conditioning variable was first built as
`barrel_pct / LEAGUE.barrel_pct` — a monotone transform of one of its own
components. That interaction was therefore **barrel², measuring nonlinearity in
barrel rate, not an archetype effect at all**, and it produced the run's only
"interaction adds" result (−0.132). Two fixes: a scale-free collinearity check on
the control columns (the Gauss-Jordan pivot test missed it, because the columns
differ by a *scale factor*), and real archetype labels joined from
`model_snapshots` (260 labelled rows: 140 BOMBER, 120 other) so the conditioning
variable is categorical and independent of barrel by construction.

**Without that catch this document would have reported a fabricated interaction
as the session's finding.**

## 5. STEP 4 — combined skill model vs the counter

The compound TB projection was built for this (see §6). Paired bootstrap is
valid at this n even though the *gate* is not.

```
n 383 · pitcher coverage 100% · base rate 0.483
resolution   skill TB 0.2718     counter 0.2647
brier        skill TB 0.2439     counter 0.2426
delta        +0.0071   CI95 [−0.0648, +0.0789]   → INCONCLUSIVE
```

**Not a win — but the first time a challenger has not LOST.** For contrast, the
same engine on hits: −0.1161, CI [−0.1892, −0.0426], excluding zero. The
difference between those two lines is the entire argument for moving to total
bases, and it is what the physics said: contact quality governs extra bases, not
whether a grounder finds a hole.

## 6. Built this session: the compound TB projection

`skillProjection` no longer refuses total bases. A deterministic bases-per-hit
multiplier made `P(TB≥2)` **exactly** `P(hits≥1)` — a relabelled hits curve — so
it was refused. It is now a real convolution: each PA yields 0/1/2/3/4 bases with
hit-type shares shifted by skill (barrel → home-run share, exit velo → doubles
and triples), convolved over a PA distribution. A BOMBER gets a 37.5% home-run
share against a slap hitter's 4.5%. Non-degeneracy is locked by test.

## 7. Verdict

- **Solo-proven set for total_bases: EMPTY.** Nothing passes; hard-hit is the
  closest and is drifting down.
- **Interaction-proven set: EMPTY.** One lead (archetype × barrel), underpowered.
- **Combined vs counter: INCONCLUSIVE at parity** — genuinely better news than
  hits, and still not promotable.
- **Nothing promoted. Counter untouched.**

## 8. Next, in order

1. **Let `statcast_history` accrue.** Nothing here can be validated honestly
   until there is a point-in-time window — a week gives a real one. This is now
   the binding constraint on the entire programme, and it is a waiting problem,
   not a building problem.
2. **Re-run this exact script** once history exists and TB clears n≥500 (383
   today, ~117 short). Both arrive on roughly the same timescale.
3. **Archetype × barrel is the one interaction worth carrying forward**, with
   real labels and adequate n.
4. **Do not re-run hits.** §5 settles it.

**Not recommended:** quoting the 0.153, lowering n≥500, or promoting on a
parity result. Parity with contamination is not a win.