So now that we have sufficiently killed the win, bunting seems to be the topic of the day. Last week there were many examples of managers employing the sacrifice bunt at silly times and it seemed to set off a fervor among those wishing to debate new ideas and old tradition. I got into some debates with followers – and you all know Brian Kenny did the same.

The basic argument against the sacrifice bunt is that giving up and out to gain a base is a bad percentage play. The facts are pretty clear on the matter. You have to consider who is batting and the exact situation of the game, but it’s usually always a bad idea to bunt with a reasonably competent position player. Below I’ve presented The Nine Worst Sacrifice Bunt Attempts of 2013. This requires some definition, but first I want to lay out the basic argument for when bunting might be a good idea because some often taking anti-bunting comments as absolute:

When To Bunt

1. When a pitcher is batting OR
2. When a very low quality hitter is up AND
3. There are zero outs AND
4. There are men on first and second AND
5. The batter has a high probability of striking out based on his skills or the opposing pitcher AND
6. One run is sufficient (i.e., you’re down one run late or tied)

The Odds Against Bunting

Here’s my post from earlier this year that outlines Run Expectancy. If you don’t like the way I explain it, just Google it. Lots of smart people have explained it.

The Rules

So the following are The Nine Worst Bunt Attempts of the year as defined like this. First, these are all bunts that have been put in play. I can’t examine the times a batter failed to get a bunt down and then the bunt sign was taken off. Second, this does not include bunts that went for hits. Bunting for a hit is great, this is about bunts in which an out was made – which is the goal of a bunt. Get on base and we don’t have a problem. Third, this is judged by Win Probability Added (WPA), which considers the game situation and the result of the play. So, if you call a bunt in a 10-0 game, who cares. If you call for a bunt in a 5-3 game with your two hitter, that’s probably silly. Finally, no pitchers. Pitchers can’t hit, so it’s fine to use them to bunt. Let’s see what happens!

There have been 1,192 sacrifice bunt attempts this season by non-pitchers. 174 have gone for hits and 39 have been turned into errors, so that’s 979 bunt attempts that resulted in at least one out. In sum, they have been worth -2.7 WPA. Here are the worst.

Let’s start with some data that sets the stage.

There we have the date and hitters. Now the opponent and situation:

All but one feature no outs and the hitting team has been trailing late or tied in each.

Alright, so a few notes. The very worst bunts are almost always the ones that include double plays or a runner getting thrown out at home somehow. Which makes sense, any time a bunt goes horribly wrong, it’s going to be more costly than a normal bunt. Martin Prado’s at #7 is the worst true sac bunt of the lot because the runner didn’t advance and Prado made an out.

So it’s perfectly reasonable to say these are poorly executed bunts. That’s true. But it’s not interesting to show you 9 very similar bunts that are all in the -4% range in the same situations. There are just so many of them. But, let me provide some summary stats to give you a better idea about the whole dataset. Of the 979 bunts that didn’t result in a hit or error, 722 resulted in a decrease in WPA, 160 resulted in no change, and 97 increased the team’s odds of winning. In other words, only 26% of sac bunts in the sample are good for the team.

So 18% of the time a batter attempts to sac bunt, he gets a hit or induces and error. That’s good. And 26% of the remaining 82% helps anyway.  All told, about one quarter of position player bunts turn out to be a good idea based on WPA. Let’s go further.

Even including all of the bunts that ended in hits and errors, 276 resulted in more than one run, 339 resulted in one run exactly, and 577 resulted in zero runs. There are good bunts, but bunting is usually a bad idea. There are bunts that mess up the defense and open the door, but they are rare. Usually when you bunt, you don’t score.

You’re welcome to keep bunting, but the odds are not in your favor.