The Value of OBP and Slugging


Kyle Terada-USA TODAY Sports

It is often said that a team with little power needs to go get it. As in, get more power. I have no source, but I think many, many people have said something similar in regards to professional wooden-bat baseball. I did a basic study regarding that claim, and it appears that the cliché is a dud. But I’ll just give you the results and let you decide for yourself.

Consider a high-OPB, low-slugging-percentage team like the 2012 Minnesota Twins. The Twinkies finished 5th in the AL in OBP, but 12th in SLG. Based on team data going back 40 seasons, if Minnesota improved by 10 OBP points as a team, then I would expect it to score approximately 26 more runs on the season. But say instead they work to improve their weakness by 10 SLG points. Then I would expect them to score just 16 additional runs.

Now consider a low-OBP, high-SLG team like maybe the Baltimore Orioles in 2012. 6th in SLG, but 11th in OBP, the Orioles could expect a 28-run increase from a 10-point bump in OBP. And like the Twins, the Orioles would only get a projected increase of 16 runs from the 10-point bump in slugging. There appears to be some marginal benefit to increasing the Orioles’ weakness, OBP, but nothing noticeable. In both cases, improving OBP seems to be the more savvy option.

It’s fair, however, to wonder if the 10-point leaps are appropriate inputs to the model. After all, it requires only about 7-to-10 OBP points to surpass three teams in the OBP standings, while it takes closer to 18 SLG points to make the same leap. I guess what it really comes down to is how much do OBP and SLG cost? Good thing I have some more data ready!

With help from Baseball-Reference, I gathered up all the free agents that signed between early November of 2011 and late March of 2012 in preparation for last season. I assessed how much their 2012 OBPs and SLGs* associated with their salaries, and here’s what I came up with. Players get paid for slugging. A player with a SLG 10 points greater than his buddy might net that player 400K additional dollars in yearly salary. A 10-point advantage in OBP, however, earns him just $300K extra.

Put another way, the top ten sluggers averaged $8.0M in salary while the top ten on-basers averaged just $6.4M. In a vacuum, 10 OBP points produces more runs than 10 SLG points, but the league still doesn’t seem to be paying out accordingly. If we go back to the original question, we can hypothesize that—based on salaries and stats from these free agents—it costs about as much for 10 OBP points as it does for 7.5 SLG points.

If we adjust our first model, we find that a 10-point increase in OBP far outweighs a 7.5-point increase in SLG. The difference is about 15 runs in favor of adding OBP to your team. That’s 1.5 wins for the same price!

In my mind, the data strongly supports the idea that OBP is still undervalued, and that the Mariners overpaid for the power they hope to get with Mike Morse.

*Even though players are being paid for their OBPs and SLGs from before 2012, their 2012 figures are what the teams actually got out of them. I controlled for each player’s age, position and ballpark to some degree. I had to eliminate players for whom Baseball-Reference had no salary data, and those that didn’t reach 100 PA. The final data set included 67 players.