A Substitute for War

Basketball philosophy

Why the faith in OPS?

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First off, I’m not a sabermatrician. I won’t pretend to be in their league in advanced baseball knowledge.  But I have a problem with their most widely used advanced batting stat: OPS.

OPS stands for On-Base Plus Slugging. In short, On-Base Percentage measures how often a player gets on base and Slugging Percentage accounts for the value of extra bases. Both these stats are fine. But I don’t see the basis for simply adding them together 1 to 1. Since they clearly aren’t worth the same, this immediately makes the stat flawed.

The consensus is OBP is worth more. It’s more important to not waste one of the precious 3 outs than advance more bases when you get on. The number I’ve heard is OBP is worth 1.8x more, though some have estimated as high as 3x and up. If true, OPS is very off. Furthermore, SLG% itself is also flawed because it weighs singles and walks the same. Singles are worth more because they advance players on 2nd and 3rd without a force from 1st, making them much more potent for scoring runs. Once again this just trips up any pretensions of accuracy for OPS.

The real basis for it is adding them together happens to coorelate pretty well with offensive production. So under the guise of “it works”, it’s stuck. I’m not buying it. Stats should be equated for reasons making sense on their own, not just because they give us the good looking answer. We shouldn’t accept flawed stats because it gives us an answer we want. Especially in baseball, a sport where eventual statistical exactness is not only possible, but realistically attainable.

In truth, OPS is a great ballpark stat. The basketball equivalent is John Hollinger’s Player Efficiency Rating (PER) or Win Shares (WS). In one number it can tell you who the MVP candidates, all-stars, and mediocore players are. It should not be treated as more.

Recently OPS+ was introduced, adjusting OPS for ballparks and giving OBP 1.2x weight. It’s not enough. It still doesn’t make sense without relying on the conclusion looking right. To me the answer is a multiplication equation involving OBP and SLG%, not addition.

My quick glance across the internet has shown me fringe sabermatricians have realized the faults of OPS and tried to develop better, multiplication based batting stats for years. Much credit to them. I’d only say not to treat OPS as gospel or the end of the line because it’s clearly not. Baseball is a sport where we can truly exact offensive value. It’s all on the paper. To treat simply adding together OBP and SLG% together 1 to 1 as enough, is selling ourselves short.

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