March 8, 2011
More From Sloan: Paired Pitching, with Greg Rubin
Last weekend's MIT Sloan Sports Analytics Conference featured a multitude of insiders and big names, but not all of the thought leaders on hand were as well-know and influential as Mark Cuban, Malcolm Gladwell and Jeff Moorad. The conference also included research paper track presentations, which gave MBA candidates like Greg Rubin an opportunity to display their analytic skills and ideas. Rubin, who attends New York University’s Stern School of Business, sat down with BP to give an overview of his paper, “Paired Pitching: How to Avoid an Arms Race.”
“If you look at the past 25 years, starting pitchers in a five-man rotation are throwing fewer and fewer innings than they used to. I think that’s primarily because of the Moneyball effect where batters are working pitch counts and you get to 100-110 pitches much more quickly. The bullpens, who are less-efficient pitchers than the starters, are now responsible for more of the game.
“The idea here is to cut your losses by saying, OK, our starters aren’t as effective as they used to be and we’re still paying them a lot of money, so instead of having a five-man rotation we’ll have a four-pair rotation where two pitchers each throw four innings per game. The first guy throws innings one through four and the second throws innings five through eight. Then you have four bullpen spots who can take the ninth inning and any extra innings.
“The reason this works is twofold. One is that if you only throw four innings, you’re only facing each batter twice on average. If you look at the data, you’ll see that the more times you face a batter in a game, the better the batter is going to do against you. In 2009, which is the data I used, pitchers averaged 5.8 innings per start and faced each batter 2.8 times.
"Let’s assume that the [first] four innings of statistics -- the by-inning statistics -- are representative of what a pitcher would throw in innings five through eight. He’s coming in fresh, and if you look at how pitchers perform over their first four innings, you’ll see that it’s much better than how they perform over the successive innings.
“83 starters threw over 150 innings in 2009, and in my study I took the eight most average pitchers. These are mostly guys in third and fourth rotation spots. Going with what those average pitchers were averaging, if you run it out over the course of the season, you would actually save 96 runs using this system. I used the Pythagenpat formula for this. What you would gain is about nine wins per season.
“There are a lot of factors that go into it, but pitchers will say they don’t throw their best stuff every pitch. They wait until they need to, to throw 100 percent. That might be part of why a pitcher might improve over the course of a game: he doesn’t want to use his best stuff early. Pitching only four innings could act as an incentive to throw your best stuff earlier in a game.
“I didn’t quantify what would happen if you pulled a guy who had thrown four perfect innings -- whether he was more likely to throw another three, four or five perfect, or near perfect, innings. Would he be better than the next guy? That’s definitely a follow-up piece of research.
“Of course, you would never see a no-hitter, let alone a complete game with this system You’d never see a lot of the things that a pitcher likes to have on his resume, and that his agent wants in order to garner him a larger contract. Because of that, you’d end up saving a lot of money by virtue of the fact that aces wouldn‘t be the same as they are now. Data shows that the average team spent 28 percent of their payroll on their five-man rotation, which constitutes 12.5 percent of the roster. A paired-pitching system would have an economic benefit as well as saving runs.”