OAA (Outs Above Average) grades each batted ball by required distance, direction of first step, and play difficulty, then sums how many more outs a fielder converted than league average.
DRS and UZR use zone-based evaluation; OAA evaluates each play continuously, which holds up better in the modern shift era when zones don't carry the same meaning.
Reference: 0 is average, +5 is solid, +10 is Gold Glove level, +15+ is historic. Negatives correspond to runs allowed via defense.
Outfielders benefit from high Sprint Speed; infielders earn OAA via reaction time and arm accuracy. Among Japanese players, Shogo Akiyama posted +10-class outfield seasons.
→ Related: Sprint Speed / DRS / UZR