NAIL-RAPM v1.2.1.3 Residualized-Target Lambda CV
This release changes exactly one modeling decision from v1.2.1.2: the player-RAPM Ridge penalty is selected from the completed source season's residualized training target rather than imported from a separate forward RAPM run.
The rest of the contract is unchanged: reconstructed regular-season stints,
forward value-conditioned aging and gap-returner priors, exposure-gated cold
starts, Medvedovsky-style additive-profile padding, the retained two-feature
non-additive context bundle, linear antisymmetric context Ridge with alpha
10,000, and the forward B2B control with alpha 10,000.
Lambda Selection
For a forecast target season \(t\), let \(s=t-1\) be its completed source season. In season \(s\), the context and B2B forecasts from \(s-1\) are first removed from the source-season training target. Three chronological folds of that residualized \(s\) data then select the player penalty:
For example, the frozen 2025-26 forecast uses \(\lambda_{2024\text{-}25}\), selected only from chronological folds within 2024-25. The fit performed on 2025-26 after that season ends is retained for the next state update and is not used to score the 2025-26 frozen cohort.
No fitted lambda schedule, state, or hyperparameter is imported from another model artifact. The only fixed profile-shrinkage constants are the accepted Medvedovsky-style padding contract shared with v1.2.1.2.
Frozen Result
The immutable comparison artifact is
artifacts/models/nail_v1212_residualized_lambda_frozen_backtest/frozen_multiseason_backtest/2023-24_to_2025-26/frozen_multiseason_backtest-2023-24-to-2025-26-20260827T221820Z-1a0cc90d.
| Metric | v1.2.1.2 imported schedule | v1.2.1.3 residualized CV |
|---|---|---|
| Regular full-game RMSE | 14.2330 | 14.2166 |
| Regular winner accuracy | 67.96% | 68.30% |
| Team net-rating RMSE | 3.2847 | 3.2351 |
| Pythagorean-win RMSE | 7.0551 | 6.9423 |
| Playoff eligible game-margin RMSE | 16.6032 | 16.5784 |
It cleared the frozen metric comparison against v1.2.1.2 and passed review of the player rankings and coefficient histories. It is the promoted production release. The frozen leaderboard contains the full metric table and ranks.
Promotion Review
The following review is calculated from the completed 2025-26 candidate fit. Its player rating is the fitted player RAPM plus the centered, exactly compilable additive-profile adjustment. It is not a frozen 2026-27 forecast.
| Rank | Player | Team | Pos. | NAIL | Prior | Season update | Additive profile | Poss. |
|---|---|---|---|---|---|---|---|---|
| 1 | Victor Wembanyama | SAS | F-C | +10.26 | +2.50 | +4.79 | +2.96 | 3,896 |
| 2 | Nikola Jokic | DEN | C | +9.70 | +4.36 | +1.39 | +3.95 | 4,786 |
| 3 | Shai Gilgeous-Alexander | OKC | G | +9.18 | +5.18 | +1.28 | +2.72 | 4,730 |
| 4 | Kawhi Leonard | LAC | F | +7.27 | +2.89 | +3.27 | +1.11 | 4,167 |
| 5 | Derrick White | BOS | G | +6.68 | +2.04 | +3.30 | +1.34 | 5,180 |
| 6 | Bam Adebayo | MIA | C-F | +6.28 | +2.61 | +2.84 | +0.82 | 5,031 |
| 7 | Alex Caruso | OKC | G | +6.07 | +1.01 | +1.83 | +3.24 | 2,125 |
| 8 | Dyson Daniels | ATL | G | +6.01 | +0.29 | +2.78 | +2.93 | 5,317 |
| 9 | Jimmy Butler III | GSW | F | +6.00 | +1.80 | +2.41 | +1.79 | 2,449 |
| 10 | Chet Holmgren | OKC | C-F | +5.96 | +3.03 | +2.63 | +0.30 | 4,129 |
| 11 | Giannis Antetokounmpo | MIL | F | +5.78 | +4.03 | +1.15 | +0.61 | 2,129 |
| 12 | Jayson Tatum | BOS | F-G | +5.30 | +4.39 | -0.20 | +1.10 | 1,046 |
| 13 | Lauri Markkanen | UTA | F-C | +5.08 | +2.90 | +2.07 | +0.10 | 3,080 |
| 14 | Donovan Mitchell | CLE | G | +4.93 | +1.57 | +0.94 | +2.42 | 4,925 |
| 15 | LaMelo Ball | CHA | G | +4.78 | +0.66 | +1.41 | +2.71 | 4,101 |
| 16 | Ausar Thompson | DET | G-F | +4.76 | +0.93 | +1.52 | +2.31 | 3,897 |
| 17 | OG Anunoby | NYK | F-G | +4.76 | +2.56 | +1.63 | +0.57 | 4,531 |
| 18 | Luka Doncic | LAL | F-G | +4.69 | +2.46 | -0.71 | +2.93 | 4,759 |
| 19 | Devin Booker | PHX | G | +4.57 | +2.19 | +2.11 | +0.28 | 4,442 |
| 20 | Franz Wagner | ORL | F | +4.49 | +4.26 | -0.81 | +1.04 | 2,190 |
| 21 | Steven Adams | HOU | C | +4.35 | +1.34 | +1.43 | +1.58 | 1,455 |
| 22 | Collin Gillespie | PHX | G | +4.19 | -0.80 | +2.85 | +2.13 | 4,626 |
| 23 | Jalen Smith | CHI | F-C | +4.15 | +0.65 | +2.20 | +1.31 | 2,316 |
| 24 | Day'Ron Sharpe | BKN | C | +4.12 | +0.84 | +0.22 | +3.05 | 2,330 |
| 25 | Karl-Anthony Towns | NYK | C-F | +4.04 | +3.04 | +0.29 | +0.71 | 4,716 |
Home Court And Back-To-Back
Home-court advantage is a season-specific home-net-rating intercept. The B2B
series is the raw coefficient for home back-to-back - away back-to-back; a
negative value means a home B2B lowers the predicted home edge.
Context Coefficients
Context weights are standardized Ridge coefficients on each home-minus-away five-man feature. Blue panels are player-attributable additive profile terms; orange panels are the two retained non-additive lineup terms.
The immutable review artifact is
artifacts/models/analysis/nail_v1213_promotion_review/nail-v1213-promotion-review-20260828T002159Z-62888daf.
Reproduction
uv run python -m nba_lineup_model.modeling.forward_nail_v1212_residualized_lambda \
--log-path artifacts/logs/nail-v1212-residualized-lambda.log
uv run python -m nba_lineup_model.modeling.nail_v1212_residualized_lambda_frozen_backtest \
--log-path artifacts/logs/nail-v1212-residualized-lambda-frozen.log
uv run python -m nba_lineup_model.modeling.nail_v1213_promotion_review
See the training guide and NAIL model contract for the complete provenance and remaining validation priorities. Proposed lineup-context additions and their resolved tests are tracked in the Non-Additive Context Feature Registry.