Box-Score Prior Panel

The box-score prior panel is the possession-native feature boundary for the next RAPM prior experiment. Each row is one player entering target season \(t\). Dynamic inputs are drawn only from season \(t-1\); target-season RAPM is a supervised label, never a model feature.

Possession-Native Rates

For a prior-season counting statistic \(c_{i,t-1}\) and reconstructed on-court possessions \(n_{i,t-1}\), the panel uses

\[ 100 \times \frac{c_{i,t-1}}{n_{i,t-1}}. \]

The first profile includes FGA, 3PA, FTA, assists, turnovers, offensive and defensive rebounds, steals, blocks, and personal fouls per 100 on-court possessions. Minutes and per-36 rates are not model features.

Shooting Stabilization

Shooting features use source-season league rates and fixed pseudo-attempt amounts:

Statistic	Pseudo-attempts
Effective FG%	300 FGA
3P%	150 3PA
FT%	100 FTA

For example:

\[ \widetilde{3P\%}_{i,t-1} = \frac{3PM_{i,t-1} + 150 \cdot \mathrm{League3P\%}_{t-1}} {3PA_{i,t-1}+150}. \]

The raw attempts remain in the panel for audit and the corresponding per-100 rates represent player role and volume.

Cold Starts

Every target RAPM player receives a row. If the player was absent in \(t-1\), lagged RAPM and box-score values are null and the row is tagged no_prior. The panel also assigns low_exposure below 500 prior on-court possessions, developing from 500 through 1,499, and established at 1,500 or more.

Static preseason features remain available for every cohort: age, experience, rookie status, draft fields, height, weight, and listed position.

Storage

data/analytical/box_score_prior_panel/
  _manifest.json
  player_prior_features.parquet
  season_cohort_summary.parquet
  league_shooting_references.parquet

The manifest records the exact validated player-season panel, target labels, label-free feature list, thresholds, pseudo-attempt settings, output hashes, and builder fingerprint.

Current Build

The current historical build covers 14,109 player-target-season rows from 1997-98 through 2025-26. Its 2025-26 target cohort contains 582 players:

Prior cohort	Players	Prior RAPM available	Prior box profile available
Established	276	276	276
Developing	109	109	109
Low exposure	77	77	77
No prior	120	0	0

This confirms that 2024-25 Stats V3 player boxes are available for every 2025-26 player with a prior season. The no-prior group is intentional and is the cold-start population for the later profile model.