NAIL-RAPM v1.2.1.1: Standard USG%
NAIL-RAPM v1.2.1.1 is a convention-correction patch to v1.2.1. It retains the same eight additive profile coordinates, two non-additive lineup terms, value-conditioned aging prior, exposure-gated cold starts, gap-returner bridge, profile padding, and Ridge estimators. It changes only the definition of usage.
Usage Contract
The prior release used a player action-event rate per RAPM on-court possession:
v1.2.1.1 uses the conventional box-score usage percentage, computed at the game level and aggregated across a player-season:
Here, \(TM_g\) is the team’s game minutes, \(MIN_{ig}\) is the player’s game minutes, and the subscript \(t\) denotes the player’s team. This makes the denominator an estimate of the team’s offensive opportunities while the player was on the court. It puts familiar player values, such as a 31.8% season for Anthony Edwards in 2025-26, on the same scale used in standard NBA analysis.
The feature receives the existing 300 pseudo-opportunity profile shrinkage and
replaces the legacy usage-event coordinate in both the additive profile and
the non-additive usage_concentration term. No target-season information is
used in frozen evaluation: each target season uses only its pre-season player
profile state and prior-year fitted context state.
Frozen Results
The strict frozen replay forecasts 2023-24 through 2025-26 from each target season’s pre-season information set. Values below are pooled over the three regular seasons; lower is better except winner accuracy.
| Model | Poss. RMSE | Poss. MAE | Eligible game RMSE | Full-game RMSE | Winner accuracy | Team NetRtg RMSE | Pythagorean-win RMSE |
|---|---|---|---|---|---|---|---|
| v1.2.1 legacy usage rate | 1.197952 | 1.141355 | 14.0246 | 14.2521 | 68.24% | 3.2706 | 7.0351 |
| v1.2.1.1 standard USG% | 1.197951 | 1.141332 | 14.0264 | 14.2516 | 68.10% | 3.2658 | 7.0279 |
The changes are deliberately small. The candidate improves full-game RMSE by 0.00055 and possession MAE by 0.000023, while eligible-game RMSE and winner accuracy are slightly worse. The predeclared paired game-block bootstrap is therefore the decision criterion rather than point-estimate cherry-picking.
| Scope | Full-game RMSE difference (v1.2.1.1 - v1.2.1) | Paired 95% interval | Gate threshold | Gate |
|---|---|---|---|---|
| Pooled | -0.00055 | [-0.00743, +0.00608] | +0.07126 | Pass |
| 2023-24 | -0.01101 | [-0.02278, +0.00067] | +0.06976 | Pass |
| 2024-25 | +0.00799 | [-0.00558, +0.02171] | +0.07189 | Pass |
| 2025-26 | +0.00096 | [-0.00834, +0.01040] | +0.07205 | Pass |
Decision
v1.2.1.1 passes the non-promotion gate, but is not promoted. Conventional USG% is cleaner as a display convention, yet it does not materially change the Minnesota-style concentration interpretation. The candidate also gives up small point-estimate advantages in eligible-game RMSE and winner accuracy. v1.2.1 therefore remains the product model and source for the website bundle.
Artifacts
- Recursive fit:
artifacts/models/forward_nail_rapm_v1211_standard_usage/2025-26/forward-nail-rapm-v1211-standard-usage-2025-26-20260823T141226Z-ddb46a76 - Frozen replay:
artifacts/models/nail_v1211_standard_usage_frozen_backtest/frozen_multiseason_backtest/2023-24_to_2025-26/frozen_multiseason_backtest-2023-24-to-2025-26-20260823T142112Z-d5cea78f - Paired bootstrap:
artifacts/models/nail_v1211_standard_usage_bootstrap/2023-24_to_2025-26/nail-v1211-standard-usage-bootstrap-20260823T142343Z-07ea4b70