Guys who should be bunting

We're barely a week into the season, and already announcers are mentioning the bunt. I was watching a game earlier this week (I honestly can't tell you which. I'm thinking it was Braves-Brewers or Nationals-Mets), and the pitcher came up to bat with a runner on base and less than two outs. The announcer promptly said, ``And up comes [The Pitcher], and he should be bunting here."

As I stated in the summary, bunting gets a lot of criticism within the sabermetric community. Manny Acta stated at SABR Analytics that he first started looking at sabermetrics after being informed that the inefficiency of the bunt by a Mets clubhouse kid in 2005. So the knowledge about the bunt has been working its way down the line over the years.

That being said, pitchers are awful hitters. I mean really, really awful. With pitchers being that bad of hitters, it has to be more beneficial to a team's run expectancy to have the pitcher bunt.

That's what you'd think, but before we assume that, let's dig into the data a little. To start, let's look at the RE24 of a plate appearance where the pitcher executes a perfect sacrifice bunt; that is, each runner advances one base and the pitcher is thrown out at first.

So, there are 6 out of a possible 24 Base-Out states where a perfectly executed sacrifice bunt results in a positive RE24. However, it's not enough to look at the RE24 for the plate appearance, we also need to look at the proportion of times a Base-Out state occurs given that the player bunted, or P( Base-Out | Bunt Occured ). Since we're focusing on pitchers, we're just looking at pitcher bunts.

So, from all this, we can get an expected value of RE24 given that a bunt occurred but taking Σ_{Base State} Σ_Outs RE24|Base-Out × P( Base-Out | Bunt Occured ). After all that, the RE24 for a bunt would be expected to be -0.1755696.

So, if a pitcher can have a better RE24/PA than -0.1755696, his team's run expectancy would be better served on average by him hitting, as counter-intuitive as that might seem. So what percentage of pitchers would you expect to be better off bunting? Of the 75 pitchers who got at least 20 non-bunt PAs over the 2013 season, there were 12 pitchers who fell below the break-even point. That still means a majority of pitches (84%) would still be better off swinging away. For those wondering, there were no position players with at least 400 PAs to fall below the threshold (The lowest value was -0.0624).

So who were the pitchers? Who were the disastrous dozen? Well, here they are, along with some of their other batting stats.

Blech. I mean really, blech. Those are some rough statistics. Only 3 of those 12 had an ISO better than .000 and there were 4 OBPs over .100. By comparison, Miguel Cabrera had the highest RE24/PA in the majors last year with 0.1153. And for those interested, of the 75 pitchers with 20+ non-bunt PAs, there were only 4 pitchers with a RE24/PA greater than 0. They were Tyler Chatwood (0.0739 in 39 non-bunt PAs), Zach Grienke (0.0308 in 70), Henderson Alvarez (0.0274 in 30), and Scott Feldman (0.0237 in 32).

Of course, there's the obvious cavaet in this: sample size. There's an incredibly small sample size in this dataset, making any conclusions difficult to draw. However, with the well-documented ineptitude of pitcher hitting, these conclusions might not be too big of a stretch, even with the small sample size.