Such was the question posed by a Twitter user in a Tom Tango thread yesterday (well, the question was "What's the…”). My response was: (TB*PA + TOB*AB)/(AB*PA) This, as you may recognize, is the formula for OPS—what actually happens mathematically when you add two fractions with different denominators (for this post, OBA = TOB/PA and SLG = TB/AB; later, W will encompass walks and hit batters).
I'm not exactly a fan of OPS+, but if you interpret a 118 OPS+ as "18% more productive than a league average hitter" rather than "18% higher OPS than a league average hitter", it is a correct statement (at least to the extent that OPS+ is a predictor of team runs scored). The negative values are an unavoidable consequence of a linear run estimator applied at extremes of offensive ineptitude, although I certainly understand why one might find them obnoxious.
While OPS is bad enough, I cringe most at the definition of OPS+ which is OBP/(leave average OBP) plus SLG/(league average SLG) minus one. How did that originate? People erroneously talk about percentages (e.g., an OPS+of 118 they say is 18% above average). This obviously breaks down for very low OPS+ which can theoretically bottom out at -100. There are pitchers with a negative career OPS+ like Sandy Koufax with a -39 OPS+. What percentage worse is he than average? 139% worse?
I'm not exactly a fan of OPS+, but if you interpret a 118 OPS+ as "18% more productive than a league average hitter" rather than "18% higher OPS than a league average hitter", it is a correct statement (at least to the extent that OPS+ is a predictor of team runs scored). The negative values are an unavoidable consequence of a linear run estimator applied at extremes of offensive ineptitude, although I certainly understand why one might find them obnoxious.
I wrote a little bit about the interpretation of OPS+ in response to Bill James' comments in his 2023 Handbook (RIP) last year: https://walksaber.substack.com/p/rehashing-runs-created-and-ops
While OPS is bad enough, I cringe most at the definition of OPS+ which is OBP/(leave average OBP) plus SLG/(league average SLG) minus one. How did that originate? People erroneously talk about percentages (e.g., an OPS+of 118 they say is 18% above average). This obviously breaks down for very low OPS+ which can theoretically bottom out at -100. There are pitchers with a negative career OPS+ like Sandy Koufax with a -39 OPS+. What percentage worse is he than average? 139% worse?