OAA
Outs Above Average — range-based defensive runs, in outs, vs an average fielder.
What OAA means
Statcast grades every batted ball by how often a play is made league-wide given the fielder's distance, direction and time, then credits the difference. 0 is average; +10 over a season is Gold Glove territory.
What counts as a good OAA
Higher is better — roughly -5 is poor, 0 average, 5 good, and 10 or better elite.
Also written
outs_above_average
Source
Statcast