Dylan Bundy’s Quiet Superpower

Dylan Bundy’s career has hardly flown under the radar. He was arguably the top pitching prospect in baseball when he debuted, and his subsequent injury troubles made the next part of his career a well-known cautionary tale. When he returned to effectiveness in the second half of 2019, then broke out in 2020, it was a story arc we’ve all seen before: the post-hype prospect makes good.

While you might know that, you probably don’t know the secret skill that’s powering Bundy’s resurgence. It’s not a high-octane fastball — he’s lost that since his prospect days. It’s not a gaudy swinging strike total — he’s no slouch in that department, but nor does he excel. What Bundy does best is loop breaking balls through the strike zone and coax batters into taking them. He might be baseball’s best at it, and the piles of free strikes he racks up power the rest of his game.

Want a quick visual before we dig into the numbers? Tim Anderson is a free swinger, but even on 0-1, he couldn’t unlock his bat against this slider:

Want it with a curveball? Watch Bundy demonstrate the low and away boundary of the strike zone to Adam Eaton:

Of course, I could show you two called strikes from anyone. But these weren’t idle choices; Bundy is truly one of the best in the business at reclaiming the strike zone from hitters. So far in 2021, he’s thrown 36 breaking balls in the strike zone, and batters have taken 16 of them, good for a 44.4% take rate. That’s above average — the league checks in around 37% in recent years — and also far below his 59.5% mark last year, the second-best mark in baseball among pitchers who threw 100 breakers in the zone.

To poorly paraphrase Tolstoy, every swinging strike on a bounced breaking ball is alike; each called strike is called in its own way. The ones you see on Pitching Ninja, the ludicrous curves that look like a fastball out of the hand before hidden underground magnets rip them downward; those either produce a swinging strike or a ball. The strategy of when to throw them is interesting, but it isn’t particularly deep; if you can afford a ball or can’t afford a ball in play, why not see if you can get a swinging strike?

Venturing into the strike zone is a more complicated task. The rewards are higher — there’s no chance of the pitch being a ball assuming you execute it correctly and the umpire cooperates. The risks, though, rise commensurately: hitters are getting bigger and stronger every year, and attacking with breaking balls means throwing slow-moving pitches in the areas where their swings are most dangerous.

Bundy is no dope, though. He understands the hitter’s mentality and pitches with that in mind. First, consider where he locates his breaking balls on the first pitch of an at-bat, when batters are at their least swing-happy:

Some are bounced, but the remainder have a clear central target: middle-down. Setting a target there gives him a margin for error — overcook the break slightly, and you might still get a strike in the bottom third of the zone. Batters are improving when it comes to offering at these first-pitch get-me-over breakers — they’ve swung roughly 35% of the time at them league-wide since the start of the 2018 season, up from roughly 30% in the preceding decade. But Bundy draws below-average swing rates despite being one of the most frequent users of in-zone bendy stuff.

Why? This is a hard question to answer, but I think it has something to do with his curveball’s inherent qualities. It has huge two-plane break — in the 80th percentile for vertical movement and 55th for horizontal. It also boasts a massive velocity gap; at 16 mph slower than his fastball, it gives batters plenty of time to recognize spin and bail. Finally, it has a telltale “hop” — a sign that many hitters have internalized to mean take. Seeing spin and automatically taking is a hard practice to unlearn, and Bundy takes advantage of it, as he did here in locking up Abraham Toro on a grooved curve:

Last year, that was basically the end of his curveball. He threw a few on 1-0 and a few on 0-1, but out of the 498 pitches he threw on the third pitch of an at-bat or later, only 12 were curves. You might see the curve early and time it, but you weren’t getting it again. From there, he broke out the slider, a pitch he uses differently; it induces plenty of swings and a healthy amount of whiffs, so batters rationally fear chasing it. Here, Derek Dietrich was mentally congratulating himself on laying off the nasty stuff — right until he realized it was down main street:

That’s the central question Bundy poses to hitters: should they commit to laying off his slider? He throws it out of the zone 59% of the time when he’s ahead in the count, and he’s lethal when batters offer at one of those — he’s compiled a 68.8% whiff rate since the start of 2019. That’s downright impressive; it’s fifth among all starters, only a hair behind leaders Dinelson Lamet and Shane Bieber.

But Bundy takes advantage of hitters’ knowledge. Swinging at Bundy’s slider is a terrible fate, and so batters do their best to lay off. 41% of the time, though, he’ll throw the pitch in the zone (league average is 33%). If you’re trying to lay off of a slider — absolutely the thought going through a batter’s mind — it’s tough to ace your recognition (hey, that’s a slider, I should take!) and then swing anyway.

I’m probably not giving Bundy enough credit when I frame this as a failure on batters’ parts. If every pitcher could do this, they all would. But Bundy shows up at the top of a slew of interesting take-related leaderboards, and that’s not by accident. Since the start of 2020, he’s eighth in called putaway percentage — the percentage of his two-strike pitches that result in a called strike three.

He’s 10th when it comes to throwing in-zone breaking balls while ahead in the count. Despite that, he’s seventh when it comes to take rate on in-zone sliders, eighth if you restrict it to pitches thrown while ahead in the count. He’s 10th in the rate at which he throws breaking balls in the upper third of the strike zone, a classic steal-a-strike location. Seriously, this feels unfair:

Why is he so good at all of these things? I have a theory. Bundy has always had excellent stuff, but he doesn’t boast the gaudy swinging strike rates that often go hand-in-hand. Something about his delivery, or his tunneling, or some other minor tell helps hitters lay off. So he’s weaponized that hesitance. If hitters are predisposed to take, Bundy is predisposed to take the strike zone away from them. In an era of increasingly nasty secondary offerings and increasingly gaudy whiff totals, Bundy exploits hitters’ pattern recognition and mental training to hit them where they’re weakest.

It helps that hitters can’t do anything even when they connect. When Bundy throws a breaking ball and it’s in the zone and a batter swings and they connect, the results still aren’t a disaster for him. He’s allowed a .375 wOBA on such pitches, roughly league average results on contact, and xwOBA will tell you he’s been unlucky to do that poorly — it checks in at .336. Plenty of upside, limited downside; it’s hardly a mystery why he keeps going back to the well.

In 2021, he’s added one more wrinkle to his game. Last year, there was a clear dichotomy: curves early in the count, sliders late. This year, he’s already thrown 13 curves in the third pitch of an at-bat or later. If you’ll recall from above, he threw only 12 all of last year. Some of these are classic uses of a curveball, like this beauty to Yordan Alvarez:

That wouldn’t look out of place from a curve-dominant pitcher, but Bundy rarely attempted that kind of pitch before this year. He’s also willing to dabble in the strike zone in these counts. Six of the 13 curves have been in the zone, including the beauty to Eaton up above and this frankly rude exploitation of Yoán Moncada’s taking tendencies:

The result of this new curveball experiment is still up in the air. We’re two starts into the year, hardly enough time to say anything definitive about a small subset of pitches. The overall trend, however, continues. Dylan Bundy doesn’t get the swinging strikes you’d expect from someone with his breaking stuff, and that’s all to the good, because he’s turned it into an under-appreciated but lethal skill.

Ben is a writer at FanGraphs. He can be found on Twitter @_Ben_Clemens.

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From these gifs, it seems like the sliders don’t move all that much but look a lot like FB so maybe they look so much like a FB that hey confuse the batter and then no swing as the ball floats over the plate.