What's the rationale behind OPS?

Question

Why has it become such a hot thing to judge a hitter's worth?

Answer 1

OPS combines on-base percentage (OBP) with Slugging Percentage (SP). These two stats are meaningful: how often does the guy get on base rather than make an out, and when they hit it, how many bases do they get. These two stats have meaning, whereas Batting Average has absolutely no meaning when judging a player (its hard to get used to, I know, but its true).
Actually, OBP is about 1.8 times as important as SP. You can figure that out just by doing basic regression analysis (if you know stats) against teams runs scored.
People who are really knowledgeable about evaluating players based on statistics ignore BA. They look at OBP and SP; OPS is a one-number shortcut. There are even more sophisticated measurements, but the best single number to measure a guy's overall hitting is OPS.

Note to Jimfo: there are some complicated formulas that take more into account just as you are suggesting. These are "Runs Created" or "Runs Created per 27 outs made". I believe you can see the rankings at ESPN.com. One thing these formulas do though, is to give only a portion of a hit's value for a SB and CS. Generally the deduction for a CS is about three times the value of a SB; a base stealer must be successful about 70% of the time to be adding value. There are some serious stat dudes who work all this out.

Answer 2

OPS is a combination of slugging and on base percentage. This give a very accurate of a hitters productivity at the plate. The rational is slugging does not take walks into account, slugging is total bases/total at bats. We all know a walk does not count as an at bat, but it is a base none the less. Conversely on base percentage does not differential a walk from a home run, and therefore it is not a good way to measure a hitters productivity. By combining the two stats we get a better picture of a hitters abilty to create runs.

Answer 3

The batter has two goals when he comes to the plate:
1. get on base (don't make an out), and
2. advance teammate baserunners.

On-base percentage is the best, readily available capture of part 1, while slugging average does a decent job of capturing part 2, as performance outcomes. As with many stats, bigger is better.

Adding the two gives us OPS. The actual number is meaningless -- it doesn't measure anything specific because the two rates have dissimilar denomenators, and we just don't do that sort of thing in real math. But the "bigger is better" meme holds true, and while one OPS value tells us nothing, having a bunch of them (say, for every qualifying hitter in the league) allows us to resolve a continuum and identify which players are doing more to put runs on the scoreboard.

OPS is far from perfect, but it has two key advantages:
1. it rolls up the two metrics which best represent the hitter's performances -- getting on base and getting himself and teammate baserunners further along; and
2. it is quick, and uses only two numbers, both readily available. Stats we can do in our heads are user-friendly.

Answer 4

the intent is to combine stats for both sluggers and guys that get on base a lot and thus have a better gauge to judge a player.

unfortunately, many sluggers also carry a high on base percentage by virtue of drawing a lot of walks and many table setter hitters(lead off and 2 hole guys) are only adept at getting on base, and not slugging(lots of doubles and homers).

i think a fairer way to compute ops is to include stolen bases minus caught stealings as part of the totals bases used to compute the slugging percentage. my thinking is that a table setter kind of player should get as much credit in ops for a single and a steal getting him to 2nd base base, as a slugger who just merely doubles to get to 2nd base.