August 26, 2007
OPS Rant
Walk Like a Sabermetrician rants against OPS, and especially against slugging percentage:
Slugging Average is not a fundamental baseball measurement. SLG may be fairly intuitive, and it certainly is venerable, but it is not something that obviously is an important measurement to have on its own. After all, slugging average doesn't really measure power, because it includes singles. So then what does it measure? It is bases gained on hits by the batter per at bat. But what is the greater significance of bases gained by the batter per at bat?
It really has none. Certainly it is good for batters to gain bases on hits; but that, in and of itself, is not a meaningful measurement. You can even look at the game in such a way that the goal is to gain bases--but in that case, the goal is not for the batter to gain bases, it is for the team to gain bases. And a team doesn't gain one base for each single on average, nor four bases for each homer, nor do the ratios between one base for a single, two for a double, etc. hold when talking about the bases gained by the team.
The point is not that Slugging Average is meaningless or stupid; the point is that it just is. It is one way of attempting to quantify the value of hits other then counting them all equally as batting average does. It is a crude way of doing so, but it does have a fairly strong correlation with runs and it is a nice thing to know.
When I worked at ESPN, I sometimes had to explain the numbers to producers of shows and pieces. Television people are about pictures, and few really care about numbers. The explanation of slugging percentage that worked for me was not in terms of bases gained by the batter (slugging percentage is the average distance traveled around the bases by a batter per at bat) but in terms of base runners. Slugging average represents the ability of a batter to drive runners a distance. The higher the slugging average, the more likely the batter is to drive a runner around to score. That explanation seemed to get through to visual thinkers. That explanation also takes care of including singles, since singles often drive runners two bases, and if you collect a lot of singles (Wade Boggs had a good slugging percentage despite a lack of home runs), you tend to move runners a lot.
Posted by David Pinto at
10:34 PM
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Exactly! Tango has some stuff on his site (tangotiger.net I think) about how many "runs" a single is worth. I think it's around .41. A walk is maybe .3 or .33. The difference there is entirely due to the single being better at moving along runners.
I've always thought they should have a stat "Total Bases advanced" or TBA. TBA would include the hitter, so if there is a runner on 2nd and the hitter hits a single that scores the runner then he would be credited with 3 on that at bat. Although I am a big fan of Ichiro, he has so many infield singles that I'm certain his average single is "worth" less than the old school singles Boggs used to hit. TBA would also credit hitters able to advance runners by hitting to the right hand side when there is a runner on second, etc.