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OPS+ is OPS (On-base Plus Slugging) adjusted for park factor and league average, scaled so 100 equals league average and 150 means 50% better than league. OPS+ is comparable across parks, eras, and seasons.
Raw OPS combines a hitter's OBP and SLG into a single number. But the same OPS in Coors Field means a worse hitter than the same OPS in Petco Park. OPS+ corrects for that by dividing by league-average OPS and adjusting for the hitter's home park.
The formula: OPS+ = 100 × ((OBP / lgOBP) + (SLG / lgSLG) - 1) / park_factor. The 100 anchor means league average is always 100. Above 100 is better than league; below 100 is worse.
The park-adjustment in OPS+ is critical for betting. A hitter posting .850 OPS at Coors loses a big chunk of that in the park adjustment, and a hitter posting .780 OPS at Petco gains some. After adjustment the Petco hitter can grade out as well as or better than the Coors hitter; the betting market sometimes overweights raw OPS without the adjustment.
For lineup comparisons across teams playing in different parks, OPS+ gives a true apples-to-apples read.
wRC+ is similar but uses a more sophisticated run-creation model under the hood (based on linear weights rather than OPS). wRC+ is generally preferred by sharp analysts because it weights each event by its true run value, while OPS+ uses the additive OPS shortcut. Both scale to 100 = league average, so values are roughly comparable.
For historical comparisons or cross-team analysis, always use OPS+ over raw OPS.
OPS+ is not an input in the current model. Its offensive inputs are wOBA-family metrics: team wOBA split by the opposing starter's handedness and confirmed-lineup xwOBA.
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