Defensive Rating

Defensive Rating (DRtg) measures the number of points a team allows per 100 possessions while a specific player is on the floor. At the team level, it is one of Dean Oliver's Four Factors. At the individual level, it attempts to isolate a player's defensive contribution to team outcomes.

Directly outcome-linked — it measures points allowed, which is what defense is actually trying to prevent. Not box-score-dependent.

Individual DRtg is heavily contaminated by lineup quality — a player on a great defensive team has a better DRtg through no individual merit. Small sample sizes amplify noise. Doesn't control for opponent quality or opponent offensive rating.

APEX uses DefOnOff (the differential between a team's defensive rating with a player on vs. off the floor) rather than raw defensive rating. DefOnOff provides more information than a player's on-court defensive rating alone because it establishes a counterfactual — how much does the defense change when this specific player enters or leaves? DefOnOff carries 90% of APEX's Defense pillar weight. Dehesa et al. (2019) independently confirm that NET/ON/OFF metrics are the dominant discriminating signal in competitive games (F > 1,499, p < .001), supporting this design choice.