Sac Bunting Summary and Redux

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:

“Ok, you want numbers, here are numbers. From The Book. Based on 2000-2004 data (very high run environment). Runner on first, no outs, RE is .906. Runner on second 1 out, RE is .700. So a bunt looks like a terrible play. But that’s not the only thing that happens on a sac. In fact that happens less than 50% of the time. If we take all the results of a sac attempt and multiply their resultant RE by their frequency we get an RE of .831. That is .131 BETTER than an out and runner advance.

So, right off the bat, a sac bunt attempt is MUCH better overall than an out and runner advance. That’s because there are so many ROE and singles (which are of course partially balanced with bad results like an out and no runner advance.) But all together it is .836. Still not as good as the original .906 though. So a bunt ATTEMPT is still bad, right? Not so fast. The .906 is for all batters combined – the league average batter. Most bunts are attempted by weaker batters. The normal (no bunt) RE for a weak batter with a runner on first and no outs is closer to the mid .800’s. So right away you can see how the bunt attempt, on average, yields around the same RE as not bunting, AS IT SHOULD!

The reason it should is because the defense has a profound effect on the RE (and WE) of a bunt attempt (and hitting away to some extent). How can we tell?

Early in a game, the total RE for a bunt attempt is .886! Late in a game it is .783. That’s because early in the game the defense doesn’t play as aggressively as late in a game in a bunt situation. They shouldn’t. That’s because the bunt late in a close game doesn’t need as high an RE to be “correct” as early in a game. You already knew that. Playing for one run late in a close game is more important than early in a game, and a sac bunt attempt is definitely a “one run strategy” to some extent at least.

But that definitely does NOT mean that bunting early is rarely correct but bunting late is sometimes or often correct. Get that notion right out of your misguided head. It doesn’t make any difference. The defense takes that “late in the game edge” away by playing further in and reducing the RE of the bunt attempt. They ALWAYS make it so that hitting and bunting yield the same win expectancy (WE) whether it is the first or 9th inning, whether there are runners on 1st and 2nd or 1st or 2nd only. It never makes a difference. The defense controls the WE of the bunt attempt.

Why wouldn’t they? If either hitting away or bunting had a higher RE or WE than the other, the offense would always choose the option which yielded the higher value, right? But then, the defense could just play further in or further back to take away that advantage. The result is always an equilibrium where the WE from hitting and from bunting is exactly the same. There are two exceptions which I’ll get to in a few more paragraphs when I sum everything up. They will hopefully make perfect sense to you.

Remember I said that the RE in 2000-2004 for swinging away (actually swinging AND bunting) for an average hitter was .906. Again, some otherwise smart people would have you believe that a bunt attempt somehow magically results in an RE of .700 (a runner advance and 1 out). What do you think the average RE after a bunt attempt is with the best bunters, the ones who bunt for a hit alot? .907! They’ve already surpassed the RE for an average batter swinging away and these guys as a group are below average hitters! It is likely that the defense is playing all the way in against these guys and it is STILL correct for them to lay down the sac bunt 100% of the time! That’s because they reach base safely almost 30% of the time including walks and the times where they switch to hitting at 2 strikes. Whatever the numbers are, if you average all the RE’s of the various results of a bunt attempt, weighted by their frequency of occurrence, you get a total of .907 – not .700, the average RE for one out and a runner on second. A bunt attempt by a great bunter is much, much better than that. Even the worst bunters, believe it or not, early in the game, produce an RE of .867, also much, much better than this .700 “out and runner advance” fiction.

So here’s the deal: It’s the last time I’m going to write about this (maybe): For real good hitters who never bunt and never should, the defense plays all the way back. You know most of these guys (although you might be surprised at who could bunt and increase their RE/WE, given where the defense is playing) and you’ve seen the defense ignore the possibility of the bunt – rightfully so most of the time. In other words, if the batter were to lay down a bunt, even with the defense playing all the way back, on the average it would be worse than hitting away. There is no such thing as a surprise bunt being effective. If a so-called surprise bunt were effective – i.e. the resultant WE were higher than not bunting – the defense by definition would be playing incorrectly.

There are batters on the borderline of this group for whom this “we’ll play back and you’ll never bunt” dual (offense and defense) optimal strategy could change depending upon the circumstances of the game. If they do, then these batters would go into Group III which I’ll get to in a minute. (For the record, there is nothing the batter can or needs to do if that changes. The defense will be the one doing the changing – they’ll move up a little.) Anyway, that’s group I.

Group II are the fast and excellent bunters. The best ones. These are the guys who get that .907 RE even though the defense clearly knows they’re bunting. For them, the defense plays all the way in and it is STILL correct for them to bunt all the time. ALL. THE. TIME. Again, there is no such thing as a surprise hitting away. If that were correct – ever – the defense would be playing too far in. Again, there are some borderline batters in this category. Some of these at the lower end of the bunt quality spectrum move into the final category (the ones who are always in equilibrium and it doesn’t matter if they bunt or not) in certain situations where the defense should not be playing all the way in – if they did, the WE from the bunt would be less than that of hitting away.

Finally, there are all the others. Group III. These are players who can bunt pretty well and/or they are not good hitters and walkers. For these batters, the defense plays in exactly the position (depends on inning, score, runners, quality of defense, pitcher, park, weather, etc.) such that bunting and hitting away yield the same WE (RE is fine to use early in a game as a proxy for WE). It doesn’t make a damn bit of difference whether they bunt, hit or fart at the plate. Some of these batters, at the extreme ends of this group’s spectrum (the ones who are very good bunters but not good enough to bunt all the time even with the defense playing all the way up AND the ones who are good hitters and/or not good bunters, but not so much that they should hit away all the time with the defense playing all the way back), will also move into Group I or II at times, depending on the game situation.

To summarize, anyone who tells you that “bunting is bad” or “bunting is good” doesn’t understand bunting. They simply don’t know what they’re talking about. This is not controversial and it’s not my opinion. While the numbers I quoted are not hard and fast (although they are based on empirical data) and there is some slop in all of 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), the basic idea is as true as anything else we have discovered about baseball in the last 30-odd years of analysis.”

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What Happens When a Batter Bunts on a 3-2 Count with a Runner on Third Base?

In Game 7 of the World Series anyone who was watching the top of the 9^th inning probably remembers Javier Baez attempting a (safety squeeze – presumably) bunt on a 3-2 count with 1 out and Jason Heyward on 3rd base. You also remember that Baez struck out on a foul ball, much to the consternation of Cubs fans.

There was plenty of noise on social media criticizing Maddon (or Baez, if he did that on his own) for such an unusual play (you rarely see position players bunt on 2-strike counts, let alone with a 3-2 count and let alone with a runner on 3^rd) and of course because it failed and eventually led to a scoreless inning. I was among those screaming bloody murder on Twitter and continuing my long-running criticism of Maddon’s dubious (in my opinion) post-season in-game tactics dating back to his Tampa days. I did, however, point out that I didn’t know off the top of my head (and it was anything but obvious or trivial to figure out) what the “numbers” were but that I was pretty sure it was a bad strategy.

Some “prima facia” evidence that it might be bad play, as I also tweeted, was, “When have you ever seen a play like that in baseball game?” That doesn’t automatically mean that it’s a bad play, but it is evidence nonetheless. And the fact that it was a critical post-season game meant nothing. If was correct to do it in that game it would be correct to do it in any game – at least in the late innings of a tie or 1-run game.

Anyway, I decided to look at some numbers although it’s not an easy task to ascertain whether in fact this was a good, bad, or roughly neutral (or we just don’t know) play. I turned to Retrosheet as I often do, and looked at what happens when a generic batter (who isn’t walked, which probably eliminates lots of good batters) does not bunt (which is almost all of the time of course) on a 3-2 count with 1 out, runner on third base and no runner on first, in a tie game or one in which the batting team was ahead, in the late innings, when the infield would likely be playing in to prevent a run from scoring on a ground ball. This is what I found:

The runner scores around 28% of the time overall. There were 33% walks (pitcher should be pitching a bit around the batter in this situation), 25% strikeouts and 25% BIP outs. When the ball is put in play, which occurs 42% of the time, the runner scores 63% of the time.

Now let’s look at what happens when a pitcher simply bunts the ball on a 3-2 count in a sacrifice situation. We’ll use that as a proxy for what Baez might do when trying to bunt in this situation. Pitchers are decent bunters overall (although they don’t run well on a bunt) and Baez is probably an average bunter at best for a position player. In fact, Baez has a grand total of one sacrifice hit in his entire minor and major league career so he may be an poor bunter – but to give him and Maddon the benefit of the doubt we’ll assume that he is as good at bunting as your typical NL pitcher.

On a 3-2 count in a sac situation when the pitcher is still bunting, he strikes out 40% of the time and walks 22% of the time. Compare that to the hitter who swings away at 3-2, runner on 3^rd and 1 out where he K’s 25% of the time and walks 33% of the time. Of those 40% strikeouts, lots are bunt fouls. In fact, pitchers strike out on a foul bunt with a 3-2 count 25% % of the time. The rest, 15%, are called strikes and missed bunt attempts. It’s very easy to strike out on a foul bunt when you have two strikes, even when there are 3 balls (and you can take some close pitches).

How often does the run score on a 3-2 bunt attempt with a runner on 3^rd such as in the Baez situation? From that data we can’t tell because we’re only looking at 3-2 bunts from pitchers with no runner on 3^rd so we have make some inferences.

The pitcher puts the ball in play 36% of the time when bunting on a 3-2 count. How often would a runner score if there were a runner on 3^rd? We’ll have to make some more inferences. In situations where a batter attempts a squeeze (either a suicide or safety – for the most part, we can’t tell from the Retrosheet data), the runner scores 80% of the time when the ball in bunted in play. So let’s assume the same with our pitchers/Baez. So 36% of the time the ball is put in play on a 3-2 bunt, 80% of the time the run scores. That’s a score rate of 29% – around the same as when swinging away.

So swinging away, the run scores 28% of the time. With a bunt attempt the run scores 29% of the time, so it would appear to be a tie with no particular strategy a clear winner. But wait….

When the run doesn’t score, the batter who is swinging away at 3-2 walks 33% of the time while the pitcher who is attempting a bunt on a 3-2 pitch walks only 25% of the time. But, we won’t count that as an advantage for the batter swinging away. The BB difference is likely due to the fact that pitchers are pitching around batters in that situation and they are going right after pitchers on 3-2 counts in sacrifice situations. In a situation like Baez’ the pitcher is going to issue more than 25% walks since he doesn’t mind the free pass and he is not going to groove one. So we’ll ignore the difference in walks. But wait again….

When a run scores on a squeeze play the batter is out 72% of the time and ends up mostly on first 28% of the time (a single, error, or fielder’s choice). When a run scores with a batter swinging away on a 3-2 count, the batter is out only 36% of the time. 21% of those are singles and errors and 15% are extra base hits including 10% triples and 5% HR.

So even though the run scores with both bunting and hitting away on a 3-2 count around the same percentage of the time, the batter is safe, including walks, hits, errors and fielder’s choices, only 26% of the time when bunting and 50% when swinging away. Additionally, when the batter swinging away gets a hit, 20% are triples and 6% are HR. So even though the runner on third scores around the same percentage of time whether swinging away or bunting on that 3-2 count, when the run does score, the batter who is swinging away reaches base safely (with some extras base hits including HR) more than twice as often as the batter who is bunting

I’m going to say that the conclusion is that while the bunt attempt was probably not a terrible play, it was still the wrong strategy given that it was the top of the inning. The runner from third will probably score around the same percentage of the time whether Baez is bunting or swinging away, but when the run does score, Baez is going to be safe a much higher percentage of the time, including via the double, triple or HR, leading to an additional run scoring significantly more often than with the squeeze attempt.

I’m not giving a pass to Maddon on this one. That would be true regardless of whether the bunt worked or not – of course.

Addendum: A quick estimate is that an additional run (or more) will score around 12% more often when swinging away. An extra run in the top of the 9th, going from a 1-run lead to a 2-run lead,  increases a team’s chances of winning by 10% (after that every additional run is worth half the the value of the preceding run). So we get an extra 1.2% (10% times 12%) in win expectancy from swinging away rather than bunting via the extra hits that occur when the ball is put into play.