That baseball managers use the sacrifice bunt too often is one of the more well-known findings of sabermetric research. After all, each team has a only finite amount of outs in a ballgame, and simple math can show that trading an out for a base will, on average, harm a team rather than help it. Consider the following table, data courtesy of Baseball Prospectus.
As you can see, a 2011 team who has a runner on first base and no outs is expected to score 0.85 runs to the end of the inning. After a sacrifice bunt, there is now a runner on second and one out. The expected runs now? 0.6492—less than what we started with. This loss of run expectancy is the reason why, in the long run, sabermetricians generally discourage teams from bunting. Of course, due to certain factors like quality of the batter/pitcher, inning/score of the game, and so on, bunting will be beneficial in some situations. But over the course of a season, it is likely that bunting will result in lost runs.
(Before I move forward, I’d like to give credit where credit is due. I was inspired by–well, nah–stole the framework for this post from Moshe Mandel’s work over at River Ave. Blues, so much thanks to him.)
So that brings us to good ol’ Cholly—how did he utilize the sacrifice bunt in 2011? In order to evaluate Manuel’s decisions regarding bunting, I did the following:
- I looked at each plate appearance than ended in a sacrifice bunt from the 2011 season, excluding pitchers (assuming that sac bunting the pitcher is one of those times when bunting is a more of an easy call rather than a decision). This leaves us with 26 sacrifice bunts from last year.
- I calculated the loss of expected runs as a result of the bunt. This is done by subtracting the expected runs after the bunt from the expected runs before the bunt.
- I looked at the amount runs that actually scored to the end of that inning.
- Finally, by comparing the actual runs score to the expected runs before the bunt, I calculated the true impact of the bunt. A positive number indicates that the bunt produced more runs than expected, making it a “good” decision. A negative number says the opposite.
So in total, Manuel’s sacrifice bunts “cost” the Phillies about a half of a run over the course of 2011. If that sounds like a tiny number, that’s because it is—a half of a run means next to nothing in the context of a full season. It appears that we can conclude that if Manuel decided not to sacrifice bunt in these situations, not much would have changed. Additionally, these numbers show that Manuel is smart with his bunts—the team only “lost” half of a run when it was expected to lose around 5 runs.
One of the more odd things that I noticed was how the Phillies performed in the innings in which Victorino sacrifice bunted. The team scored 11 runs in these innings, vastly outperforming the 5.3131 expected runs. I often voiced frustration every time Manuel would choose to bunt the team’s most productive hitter, yet in the end these decisions seemed to have worked in the Phillies’ favor. Still, I wouldn’t be quick to say that bunting Victorino is a good idea. In addition to being plagued by an admittedly small sample size, the results of his six bunts are confounded by the fact that he typically bats at the top of the order, making these innings more likely to be filled with good hitters.
Regardless, like I said before, Manuel’s decisions to sacrifice bunt seem to have had no real negative effects on the team last season.