Devin Williams and the Unicorn Changeup

The inspiration for a new pitch design can strike at any moment. Usually, it’s a coach or a teammate sharing their well-earned wisdom or tricks-of-the-trade. Sometimes a new pitch is developed during bullpen sessions as a pitcher tinkers with a new grip or finger placement. More recently, pitch design has been outsourced to technologically advanced pitching labs like Driveline, where pitchers try to harness all the data at their disposal to create the most effective pitch possible. But for Devin Williams, the design for his changeup didn’t come from any of the normal avenues. Instead, it was developed on the neighborhood fields of his childhood.

In a recent media session, he described how he had thrown a version of what is now his changeup since he was growing up:

“I started throwing like that as a kid. Like, when I played catch with my friends, just to mess with people, trying to make them miss the ball when I threw it to them. That’s what turned into my changeup. I’ve had that since I was maybe 10 years old.”

Changeups come in a variety of types and styles. There’s the classic change that relies on a high velocity differential off the fastball to create deception. The circle change adds tumbling vertical movement to further differentiate the pitch from a heater. Felix Hernandez’s cambio redefined what a modern changeup could look like without the trademark velocity differential. Williams’ changeup is an entirely different beast, making it a changeup unique in baseball — the unicorn changeup.

Based on Harry Pavlidis’ research into what makes a changeup effective, we know that a large velocity differential is beneficial for inducing swings and misses. But he also found that changeups that have a wide separation in movement profiles from the pitcher’s fastball can also be effective, particularly at generating groundball contact. Here’s a table showing the greatest velocity differentials for all pitchers who have thrown at least 50 changeups this season:

Changeup-Fastball Velocity Differential
Pitcher Fastball Velocity Changeup Velocity Differential
Dylan Cease 97.6 83.1 14.5
Spencer Howard 94.1 79.6 14.5
Lucas Giolito 93.8 80.7 13.1
Alex Claudio 85.4 72.5 12.9
Matthew Boyd 91.8 79.1 12.7
Devin Williams 96.4 84.2 12.2
Kris Bubic 91.7 80.1 11.6
Brad Boxberger 92.7 81.2 11.5
Tyler Clippard 89.3 77.9 11.4
Jacob Waguespack 92.5 82.2 10.3

Williams’ changeup has the sixth highest velocity differential in baseball this year. It definitely helps that he throws his fastball with the second highest average velocity among the pitchers on that list above. That’s a solid foundation to build off of but he also adds a ridiculous movement profile to make the pitch unlike any other in baseball. Here’s what it looks like when thrown to a right-handed batter:

And here’s what it looks like when thrown to a left-handed batter:

His changeup tumbles 40.2 inches and breaks 18.1 inches on average. Both of those marks represent the fourth-most raw movement of any changeup thrown more than 50 times this season. When compared to changeups thrown around his average velocity, his has the most horizontal movement out of any of them, 37% more than average. A changeup with that much vertical and horizontal movement is definitely an outlier, as David Adler of showed.

In many ways, his pitch acts more like a left-handed curveball than a true changeup from a right-handed pitcher. When you see how he grips and releases the pitch, you can begin to understand that unique movement profile a little more:

His grip and wrist pronation give the pitch tons of side spin, which imparts all that horizontal movement. That gives the pitch an average spin rate of 2827 rpm, easily the highest spin rate for a changeup in baseball by nearly 400 rpm. It’s a spin rate you’d expect to see from a high-spin breaking ball. Normally, you’d expect a changeup to have a low-spin rate, giving it the vertical drop that comes with a low amount of backspin. But Williams’ side spin imparts both vertical and horizontal movement at a very effective rate with 82.5% active spin.

A few years ago, Trevor Bauer spent his offseason attempting to craft a changeup with the exact qualities Williams’ possesses. This process was covered by Lance Brozdowski for The Hardball Times.

“Trevor Bauer spent the majority of his 2018 offseason figuring out how to do something foreign to him: side spin a baseball. Changeups consist of both run and vertical drop. Run is horizontal movement in toward a right-handed hitter. Changeups can possess all run and little vertical drop or no run and a lot of vertical drop. With true side spin on a baseball, you create horizontal movement and essentially eliminate the lift component that can limit downward movement. ‘Somewhere in that range of axes is where the ideal changeup lives,’ Bauer told me.

Bauer’s difficulty side-spinning a changeup came from his hand position upon release of the ball. For a pitch to truly side spin and achieve Bauer’s goal, the ball can’t have backspin because it creates “lift” on the pitch and takes away from potential downward action. According to Driveline Baseball’s manager of pitching, Bryan Leslie, there are two ways to kill the lift component on a changeup. The first is to reduce the spin of the pitch, and the second is to change the axis of the spin. A perfectly backspun fastball, spinning end-over-end toward the plate, has essentially none of its spin converted to horizontal movement. By turning the ball away from 12 o’clock and toward one, two, or three o’clock on a clock face, lateral movement is created, and lift on the ball is reduced.”

Based on the slow mo screencap from Rob Friedman embedded above, Williams’ changeup grip looks similar to what has become known as a Vulcan grip. That grip was what Bauer was working on in his quest to find the ideal changeup. While he and other pitchers who use a similar grip attempt to impart side spin ineffectively, Williams’ wrist pronation gets him all the way there.

All of the physical characteristics of Williams’ changeup — velocity differential, movement profile, and spin rate — are all elite on their own, and taken together make his changeup a one-of-a-kind. Here are the percentile ranks for each of the characteristics:

Devin Williams, Changeup
Characteristic Raw Data Percentile Rank
Velocity Differential 12.2 mph 97
Vertical Movement 40.2 inches 97
Horizontal Movement 18.1 inches 97
Spin Rate 2827 rpm 100

They’re all 97th percentile or higher. Spencer Turnbull and Jake Arrieta both throw changeups with above average tumble and run but their velocity differential is far lower than Williams’ and they both throw traditional low-spin changeups. Dylan Cease’s changeup has the best velocity differential in baseball but it barely breaks at all.

So is this unicorn changeup effective? You bet. When batters swing at the pitch, they miss 58.9% of the time. That’s the highest whiff rate for any changeup thrown more than 50 times by almost 10 points. And if a batter makes contact with the pitch, they’re likely to put it on the ground; the pitch has a groundball rate of 63.6% on 11 balls in play. Williams has collected 21 strikeouts off the pitch and he hasn’t allowed a single hit off it.

His changeup isn’t his only plus pitch either. His mid-90s four-seam fastball has an above average amount of ride and tons of armside run as well. Here are the percentile ranks for his fastball’s physical characteristics.

Devin Williams, Fastball
Characteristic Raw Data Percentile Rank
Velocity 96.4 mph 90
Vertical Movement 12.6 inches 93
Horizontal Movement 9.7 inches 74
Spin Rate 2385 rpm 76

His fastball generates a whiff 41.3% of the time a batter swings, well above the league average whiff rate for a four-seam fastball. Those insane results have propelled his strikeout rate up to 53.4%, the highest in baseball among all pitchers who have thrown a similar number of innings.

While he was coming up through the Brewers farm system, scouting reports had his upper-80s slider as his best secondary offering with his changeup an afterthought. Between his brief call up last year and his breakout season in 2020, he’s thrown all of 14 sliders (or cutters as Baseball Savant classifies them). But with such an effective weapon in his changeup, there’s little need to mix up his arsenal with a third pitch.

With Corey Knebel a shell of his former self after returning from Tommy John surgery, Williams has given the Brewers another elite bullpen arm to pair with Josh Hader. If Craig Counsell wanted to start using Hader in a fireman’s role again like he has the last few years, Williams gives him a dominant arm to use in the eighth or ninth inning or in high leverage situations. With the best, most unique changeup in baseball, he’s well equipped to thrive as one of the best relievers in baseball this year.

Jake Mailhot is a contributor to FanGraphs. A long-suffering Mariners fan, he also writes about them for Lookout Landing. Follow him on Twitter @jakemailhot.

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Hader still hasn’t given up a hit. Williams out here with Bugs Bunny asking for pointers. Fastball Freddy has looked like a legit bullpen weapon. Suter comes in working faster & throwing slower than just about anybody in MLB (& heads up a pretty sick bullpen drum circle). Drew Rasmussen’s stuff looks to be of the high leverage variety.

When David Phelps & his 60 ERA-/40 xFIP- is expendable while your team is still around 50/50 postseason odds…you might have a stacked bullpen.

If the Brewers start hitting to their projections, they might just have another insane September run up their sleeves.


No more David Phelps mentions please. Cubs couldn’t even pick him up for 4 mil crying poor. One of the worst moves of the off-season. Bullpen was a glaring weakness. They gave up hatch who would be their best bullpen arm to decline a cheap option.