Adjusted OPS
OPS against the league and park, where 100 is average.
What it actually is. On-base plus slugging, adjusted for the ballpark the player hit in and the run environment of his league that year, then scaled so that 100 is exactly average every season.
What a scout reads off it. This is the number that makes cross-era comparison honest. A .900 OPS in 1968 and a .900 OPS in 2000 are not the same accomplishment, and OPS+ says so: it is the distance from his own peers, in his own park, in percent.
Where the lines are. 100 is average by construction. 150 means half again better than league average, which is a star; 130 is a very good regular; 75 is a bat that has to be carried. Babe Ruth's career 206 is the record and Barry Bonds's 268 in 2002 the highest single season.
How it lies to you. The park adjustment is a season-long average, so it does not know that a left-handed pull hitter gets more out of a short right field than his right-handed teammate does. It corrects the building, not the fit.
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