Methodology

Advanced stats

Six stats beyond points and rebounds, computed every morning from the box scores. Each one with its formula, a worked example and what it can't tell you.

Effective field goal % (eFG%)

Field goal percentage that gives a made three its extra point: a three counts as 1.5 field goals. It shows shooting quality without free throws.

eFG% = (FGM + 0.5 × 3PM) ÷ FGA

Worked example: 8-of-18 with 3 threes: (8 + 1.5) ÷ 18 = 52.8%.

Limits: Ignores free throws (true shooting % counts them).

Possessions and pace

A possession ends with a shot that isn't rebounded by the offense, free throws or a turnover. Pace is possessions per 40 minutes: it tells you whether a team plays fast or slow, which puts every per-game number in context.

Possessions = FGA − ORB + TOV + 0.44 × FTA
Pace = 40 × (team poss + opponent poss) ÷ 2 ÷ (team minutes ÷ 5)

Worked example: 60 FGA, 10 offensive rebounds, 15 turnovers, 20 FTA: 60 − 10 + 15 + 8.8 = 73.8 possessions. With the opponent at 70.2 in a 40-minute game, pace = 72.0. The same game in overtime (45 minutes) is a pace of 64.0.

Limits: An estimate from the box score; the 0.44 free-throw factor is the standard one (see true shooting %).

Offensive, defensive and net rating

Points scored and allowed per 100 possessions, and the difference. The fairest way to compare teams that play at different speeds.

Offensive rating = 100 × points ÷ possessions
Defensive rating = 100 × opponent points ÷ possessions
Net rating = offensive − defensive

Worked example: 75 points in a 72-possession game = 104.2 per 100.

Limits: Not adjusted for opponent strength; the Freeman Rating is.

Usage rate

The share of her team's possessions a player finishes with a shot, free throws or a turnover while she's on the floor. Who the offense runs through.

Usage = (FGA + 0.44 × FTA + TOV) × (team minutes ÷ 5) ÷ (minutes × (team FGA + 0.44 × team FTA + team TOV))

Worked example: 15 FGA, 5 FTA, 3 turnovers in 32 minutes, for a team with 60 FGA, 20 FTA and 15 turnovers in a 40-minute game: (15 + 2.2 + 3) × 40 ÷ (32 × 83.8) = 30.1%. Five players who each play every minute always add up to 100%.

Limits: High usage isn't good or bad by itself; read it with true shooting %.

Assist rate and assist-to-turnover ratio

Assist rate is the share of teammates' baskets she assisted while she was on the floor. AST/TO is assists per turnover.

Assist % = AST ÷ ((minutes ÷ (team minutes ÷ 5)) × team FGM − FGM)
AST/TO = AST ÷ TOV

Worked example: 6 assists and 6 baskets in 30 of 40 minutes, on a team with 26 baskets: 0.75 × 26 − 6 = 13.5 teammate baskets, so 6 ÷ 13.5 = 44.4%. 6 assists and 3 turnovers = 2.0 AST/TO.

Limits: Scorekeepers award assists differently from arena to arena. AST/TO is blank with no turnovers.

Offensive and defensive rebound %

The share of available rebounds a player or team grabs on each end. Fairer than raw rebound totals, which depend on minutes and how many shots were missed.

Player ORB% = ORB × (team minutes ÷ 5) ÷ (minutes × (team ORB + opponent DRB))
Team ORB% = ORB ÷ (ORB + opponent DRB)
(Defensive: swap offensive and defensive rebounds.)

Worked example: 3 offensive rebounds in 30 minutes, with the team getting 10 and the opponent 25 defensive: 3 × 40 ÷ (30 × 35) = 11.4%.

Limits: Team rebounds credited to no player aren't in the box score, so rates run slightly low.

Inputs and source

Box scores: balldontlie (licensed; not official league data). Pulled Nov 7, 2026, refreshed every morning. Team and opponent totals are the sums of the players' lines.
Season numbers add up every game first and divide once (not an average of game averages).
Matching games: pace, ratings and rebound rates need both teams' box scores, so they count only games where both are in the data (a Division I team's games against lower-division schools often aren't). A player's usage and assist rate count the games where her minutes are reported, against her team's totals per minute.
Team minutes are 200 a game, 225 with one overtime and 25 more for each extra overtime, unless the box score reports every player's minutes.
Code: pipeline/metrics/formulas.py, tested against these worked examples before every publish. Impossible values (a rate over 100% for a player with 40+ minutes, a pace outside 40–120) stop the publish.