APER is a modified version of PER that attempts to correct for position-based scoring bias by adjusting a player's raw PER relative to the average PER at their position. If the average center has a PER of 17 and a specific center has a PER of 21, their APER reflects that 4-point surplus rather than the raw 21.
APER = PER − Position Average PER + League Average PER
The adjustment normalizes each player to a common baseline, making cross-position comparisons theoretically more valid than raw PER.
Partially addresses PER's well-documented big-man bias by accounting for positional context. Marginally better than raw PER for cross-position comparisons.
Inherits all of PER's fundamental flaws: arbitrary weighting coefficients, essentially no meaningful defensive component, overvaluation of volume scorers and high-rebounding centers. Position adjustment is only as good as the position labels used, which are themselves problematic as the modern game increasingly features position-less players.
APER is not used in APEX. Adjusting a flawed metric for position does not fix its underlying methodology. Jewell et al. (JQAS) confirm that BPM is more robustly significant than PER-adjacent metrics as a predictor of player value. APEX uses BPM, EPM, LEBRON, and DARKO DPM — metrics with superior validation — rather than any variant of PER.