Sac Bunting Summary and Redux

Posted: April 19, 2017 in bunting, Game Theory

There’s been some discussion lately on Twitter about the sacrifice bunt. Of course it is used very little anymore in MLB other than with pitchers at the plate. I’ll spare you the numbers. If you want to verify that, you can look it up on the interweb. The reason it’s not used anymore is not because it was or is a bad strategy. It’s simply because there is no point in sac bunting in most cases. I’ve written about why before on this blog and on other sabermetric sites. It has to do with game theory. I’ll briefly explain it again along with some other things. This is mostly a copy and paste from my recent tweets on the subject.

First, the notion that you can analyze the efficacy (or anything really) about a sac bunt attempt by looking at what happens (say, the RE or WE) after an out and a runner advance is ridiculous. For some reason sabermetricians did that reflexively for a long time ever since Palmer and Thorn wrote The Hidden Game and concluded (wrongly) that the sac bunt was a terrible strategy in most cases. What they meant was that advancing the runner in exchange for an out is a terrible strategy in most cases, which it is. But again, EVERYONE knows that that isn’t the only thing that happens when a batter attempts to bunt. That’s not a shock. We all know that the batter can reach base on a single or an error, he can strike out, hit into a force or DP, pop out, or even walk. We obviously have to know  how often those things occur on a bunt attempt to have any chance to figure out whether a bunt might increase, decrease or not change the RE or WE, compared to hitting away. Why Palmer and Thorn or anyone else ever thought that looking at the RE or WE after something that occurs less than half the time on a bunt attempt (yeah, on the average an out and runner advance occurs around 47% of the time) could answer the question of whether a sac bunt might be a good play or not, is a mystery to me. Then again, there are probably plenty of stupid things we’re saying and doing now with respect to baseball analysis that we’ll be laughing or crying about in the future, so I don’t mean that literally.

What I am truly in disbelief about is that there are STILL saber-oriented writers and pundits who talk about the sac bunt attempt as if all that ever happens is an out and a runner advance. That’s indefensible. For cripes sake I wrote all about this in The Book 12 years ago. I have thoroughly debunked the idea that “bunts are bad because they considerably reduce the RE or WE.” They don’t. This is not controversial. It never was. It was kind of a, “Shit I don’t know why I didn’t realize that,” moment. If you still look at bunt attempts as an out and a runner advance instead of as an amalgam of all kinds of different results, you have no excuse. You are either profoundly ignorant, stubborn, or both. (I’ll give the casual fan a pass).

Anyway, without further ado, here is a summary of some of what I wrote in The Book 12 years ago about the sac bunt, and what I just obnoxiously tweeted in 36 or so separate tweets:

  1. snapper says:

    I am highly dubious that the defense has sufficient information so that they can always position themselves such that the RE is the same for a bunt or hitting away.

    Everyone involved is guessing as to what the true porbabilities are, and the defense is also guessing as to what is the correct positioning. Given the very small number or trials, and the uncertainties about probabilities, you could easily have a situation where either the offense or the defense, or both, is acting sub-optimally, and no one would even know about it.

    There’s no “market mechanism” here to enforce an equilibrium.

    • MGL says:

      You mean like this: “players and teams are sometimes out of equilibrium or adopt sub-optimal strategies for various reasons, although when they do, one or the other team is definitely exploitable…” (I wrote that at the end of the essay.)

      Of course what you said is correct. I could have added, as you say, “It is impossible for a team to know exactly where to play such that they are at a GTO (game theory optimal) position, but the data suggest that overall they are pretty darn close, which is not surprising (they have 100 years of experience to guide them). And while overall they may be pretty darn close, there are no doubt lots of instances where either the offense or defense, or both, are completely out of “alignment or equilibrium” (either the defense is playing to far in or too far back, or the offense is responding sub-optimally to the position of the defense).”

      How’s that?

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