GUIDES · BETSLIP DOCTOR
Why can raw plus-minus and NBA net rating tell different stories about a lineup?
Because the measures use different units. A lineup can have the same raw point differential over two samples but a different Net Rating if the samples contain different possession totals. Keep the same on-court lineup and interval when calculating both.
For Bettors and cappers interpreting basketball statistics · Updated
Plus-Minus counts points while on the floor
The NBA glossary defines Plus-Minus as the point differential when a player or team is on the floor. It is a cumulative difference in points for and against during that sample, not a rate per possession.
Net Rating normalizes the differential
Net Rating measures point differential per 100 possessions; for a player, the glossary scopes it to the team’s differential while that player is on court. Its formula is Offensive Rating minus Defensive Rating.
A raw differential and its possession-scaled rate can rank two lineups differently. Compare the same lineup interval for both calculations, and treat minutes, opponents and lineup context as description rather than proof that one player caused the difference.
Two fictional lineup intervals
Hypothetical lineup A’s interval contains 40 team possessions and 40 opponent possessions: its team scores 44 points and allows 38. Its Plus-Minus is +6; the equal-possession differential scaled to 100 is (6/40)×100 = +15 Net Rating. Lineup B’s interval contains 30 team possessions and 30 opponent possessions: it scores 33 and allows 27. Its Plus-Minus is also +6, while the differential scaled to 100 is (6/30)×100 = +20. Each raw and rate value uses the same on-court interval for that lineup; all counts are invented and do not attribute results to a particular player.
Related questions
Does a higher Net Rating mean the player caused the lineup’s scoring margin?
No. Net Rating is a possession-scaled team differential in the player’s on-court minutes. It describes that shared sample and does not establish individual causation.