Mark Hoffman/Milwaukee Journal Sentinel/USA Today Network via Imagn Images

Last week, the illustrious Ben Clemens wrote about the state of the bunt, because the state of the bunt, as it turns out, is strong. Hitters are bunting more often, picking their spots better, and finding greater success. It’s a bunting renaissance. He didn’t appear in Ben’s article, but Milwaukee’s David Hamilton is at the forefront, leading the league with 10 bunt hits and 23 total bunts. It’s just the 12th time this decade a player has reached 23 bunts in a season, and we’re only halfway through June! Ben noted that 74.1% of bunts have been successful – meaning the bunt resulted in either a hit, an error on the defense, or a sacrifice – the highest mark in the universal DH era. With so much bunt in the air (and on the ground), I got to wondering how pitchers can fight back.

The first line of defense is to alter your positioning. You bring your third baseman in, play the corners in, put on the wheel play. But I wanted to come at it from another angle. If you’re a pitcher, and you want to make sure the batter at the plate doesn’t get a successful bunt down, what can you do? The two biggest things you can control are your pitch type and location. I dug into the Statcast data on bunts and attempted bunts over the past 18 years. This is not earthshaking research, and some of what I found is fairly intuitive, but I’m not sure I’ve ever seen it laid out, and I definitely haven’t seen any numbers behind it.

As Ben noted, most bunts are successful. Since 2008, 69.8% of bunts in play have been successful, which again means a hit, an error, or a sacrifice. Whether or not you approve of sacrifice bunting, we’re counting it as a success because it’s what the bunter wanted. When there’s nobody on base and the batter gets a bunt down in fair territory, they reach base 46.3% of the time. A .463 BABIP is pretty darn good, and it more or less holds true across all pitch types:

If you’re on the mound against a David Hamilton type, I’m not sure whether knowing that curveball bunts in play have a success rate that’s 3.9 percentage points higher than four-seamers and 4.4 points higher than offspeed pitches will affect your decision-making. That sounds like a pretty small difference. Still, think of it as 40 points of batting average or on-base percentage. Maybe that should be enough to affect your pitch selection. Curveballs aren’t as bad as this table makes them seem, but we’ll get to that a bit later.

That’s bunting for a base hit with the bases empty, but what about bunting with runners on base? We’ll leave out situations with a runner on third, because that’s its own can of worms, but here are the success rates by pitch type:

If you manage to get a bunt down in fair territory with runners on base, you’ve got a nearly 80% chance of success. Once again, the spread between pitches doesn’t seem all that large, but if you’re sure the batter is going to try to sacrifice, it might be useful to know that the success rate of four-seamers is 4.9 percentage points lower than that of offspeed pitches. Five percentage points seems like an awful lot when success means that one runner will be moving into scoring position at the very least.

As for why four-seamers are the toughest to get down, that part may be intuitive. Four-seamers rise – or at least, they fight against gravity the hardest – which gives them the best chance to contact the top of the bat, which leads to airborne bunts. Here are the rates of popouts and lineouts per bunt in play:

Four-seamers are ahead by a mile here. If you throw a four-seamer and the batter puts it in play, they have a nearly 10% chance of popping out. That’s awfully high, and you can make it even higher by locating the pitch well. As you’d expect, higher pitches get popped up more often. Here are the same numbers, but this time only for pitches in the upper third of the zone or just above the edge:

In all, 57% of bunts that turn into popouts or lineouts are four-seamers. If you’ve got your third baseman playing really shallow, or if you’re a particularly athletic pitcher, throw a four-seamer. It’s your best chance of inducing a back-breaking popout bunt. All of this is intuitive enough. After doing all my research, I asked a friend who’s much smarter about baseball than I am what he thought the best pitch to throw to a bunter was. He didn’t hesitate: fastball up and in. So far all the numbers I’ve shown you bear that out, but I’ve only shown you numbers for balls in play.

I told you before that curveballs aren’t as bad as they seem. They tend to leave the bat on a downward trajectory, which is great if you’re trying to get the bunt down. But before they leave the bat on that downward trajectory, they have to actually make contact with it. It turns out that’s a challenge, because as with regular swings, vertical break is the key to missing bats on bunts. A curveball’s main job is to drop, and they tend to drop below the bats of bunters. This one is pretty intuitive, but these fantastic diagrams, courtesy of Baseball Prospectus’s illustrious Bradley Woodrum help to demonstrate why dropping is particularly helpful in missing bats (and before you accuse me of only knowing one adjective, please consider the possibility that both Ben and Bradley really are illustrious):

Bradley wasn’t writing about bunts when he made these diagrams, but I think you could argue that they fit even better for bunts than regular swings, since hitters tend to alter their bat angle less when they’re bunting than when they’re swinging normally. The table below shows the rate of fouled or missed bunts for each pitch type. Curves are on top, and it’s not particularly close:

If your goal is to make it as hard as possible for the batter to get a bunt down in fair territory, throw a curveball. A curveball is 32% more likely to create a whiff or a foul than a four-seamer. More specifically, throw a low curveball. The average successfully bunted curveball crosses the plate at a height of 2.65 feet, whereas the average curveball that’s fouled off or missed on a bunt attempt has a height of just 2.01 feet.

First I showed you the success rate on bunts in play, then I showed you the whiff and foul rates. Now, let’s fold all bunt attempts together. Here’s the success rate on a per-pitch basis:

Four-seamers may have the best chance of inducing a popup, but because they miss so few bats, they’re the easiest to turn into a successful bunt. If you throw a four-seamer to a batter who’s squared to bunt, they are, again, 32% more likely to reach base or advance a runner than if you throw a curveball. I even ran the numbers insolating four-seamers up and in, just to be sure. I looked at just the zones highlighted in the diagram below, Attack Zones 1, 2, 11, 12, 21, and 22, and only to right-handed batters:

If we limit things to these perfectly located up-and-in four-seamers, the success rate is actually higher! It’s true that the success rate on bunts in play drops slightly — it’s two percentage points lower on these up-and-in four-seamers than on all other four-seamers — but these pitches are much, much easier to bunt in play. The rate of fouled and missed bunts drops all the way from 56% to 45%. It turns out that when you square around to bunt and the ball is coming right at your face, you are highly motivated not to miss it. That raises the overall success rate to 62%. They may make batters look extremely uncomfortable, but all of a sudden, these four-seamers up and in are even easier to bunt, and that doesn’t account for all the hit-by-pitches that result from batters squaring to bunt and being unable to avoid a fastball up and in. I don’t have a way to determine how often that happens, but we’ve all seen it plenty of times, and I suspect the number isn’t insignificant.

We don’t have numbers on pitches where the batter squares up to bunt and then takes the pitch, which is a huge hole here. I suppose it’s possible that four-seamers notch more called strikes and fewer balls than other pitches, which would increase their value. Still, even if that’s the case, it would take a whole lot of called strikes to make up the difference.

If you’re sure the batter is bunting no matter what, that they’re going to take multiple cracks at it and even bunt with two strikes, then busting them up and in with a four-seamer early in the count may be the smart play. They’ve got a good chance of getting one of those three tries down, so throwing the pitch with the lowest success rate on bunts in play makes sense. But once you get to two strikes, or if it’s early in the count and you just want to make sure that the bunt never gets down at all, the breaking ball is the smart move.

All statistics are current through games on June 12.