Aaron Ashby, Athletic Freak: How a Mechanical Tweak Has Taken Brewers Lefty to New Best Level

The stuff is filthy, but Aaron Ashby's raw movement isn't the reason why he flummoxes hitters. It's always been about the fact that that movement comes from, well, that movement—the funky delivery from which each pitch explodes like a starship coming through a wormhole.

Walk through the Brewers clubhouse, and Ashby looks perhaps less like an elite athlete than anyone else in the room. He doesn't have rippling biceps, or even broad shoulders. He's not as tall or as thick-thighed as most pitchers (and nearly all power pitchers) are. You know those specs he wears on the mound? He doesn't even wear glasses off the field. To turn into Super-Man, he puts on the Clark Kent glasses. He has just one thing going for him—his superpower—and he's learned to make the absolute most of it: almost nobody can move quite like him.

In many athletic endeavors, there are basically two key things that set the constraints for a person, and they work against one another, so it's all about finding a balance. One is strength. Without at least a modicum of strength, you'll fall short in most things. You have to be strong to run fast. You have to be strong to jump high. You have to be strong to throw hard. Building muscle mass and training yourself to turn that strength into explosiveness is vital for any aspiring elite athlete.

The other thing, though, is mobility—or flexibility, if that's what you prefer to call it. Almost any athletic endeavor—including the ones I just ticked off, and certainly including more complex ones, like pitching—also requires that one maintain excellent range of motion. Flexibility and strength can get in one another's way, though. Bigger muscles make it harder to move fluidly. To a point, you gladly pay that price, because strength is essential. On the other hand, you can emphasize flexibility and assiduously avoid bulking up, in order to optimize range of motion. That often means more speed, but it means less strength. 

Ashby is stronger now than when he came into the league. He's added functional strength to reduce the risk of injuries like the major shoulder trouble that sidelined him for a year and threatened to end his career before it really began. That shows up in his delivery, too, in ways that can look small but actually turn out to be big. For instance, look at his lower half in these snapshots of his delivery—from 2021, on the left, and from this season, on the right.

With greater core and leg strength, Ashby is staying on line toward the plate better than he used to. Notice the way his back leg is driving more, rather than his foot turning all the way over and his leg leaking out to the left as he comes through. His posture is a bit more upright, too; he's not listing to the right as much. All of that comes from being stronger.

Strength isn't the foundation of his brilliance, though. It's just a brace. As you can also see above, mobility is king. Ashby's contortions on the mound are the key to his dominance and to understanding it. His flexibility, which is achieved precisely by not having massive muscles and by keeping a modicum of stringy svelteness about him, is what sets Ashby apart. Here's how.

This is a "typical" high-slot left-handed reliever—Yuki Matsui, of the Padres, whom the Brewers saw in the NLDS. He's releasing the ball from his standard arm angle (around 54°), which is nearly identical to Ashby's own season-long average.

When you think of an over-the-top hurler, this is what you tend to envision. Good, sturdy posture and a high angle allow the pitcher's hand to stay behind the baseball perfectly, giving them great carry on four-seam fastballs. When they want to throw a breaking ball, this delivery also makes it relatively easy to supinate and impart spin. I've added a red line to show the approximate angle between the midpoint between the shoulder blades and Matsui's hand, and a yellow one to show the angle of his spine. 

Compare the above to Ashby, shown here pitching against the Cardinals in July.

This is a whole different thing. It's enough to make you wonder whether the nominal arm angle listed for Ashby is even a fair representation of the way he pitches. After all this time, is he really a high-slot hurler? The answer is still 'yes', in some important ways, but as the red line shows, it's not so in terms of sheer shoulder abduction. Matsui truly comes over the top. Ashby comes around his body, as much as over it. As the yellow line here shows, he just tilts his spine so much that doing so looks like throwing over the top.

From that actual arm angle, pronating is a more natural movement. That allows Ashby to generate heavy action on his sinker, but explains why he doesn't get much carry on his four-seamer (and, thus, why he's never thrown one very much). It's an extremely deceptive way to pitch, but it's only possible because Ashby is exceptionally flexible. Watch that video of him pitching to Lars Nootbaar, instead of just scoping a still, and you can see it.

 

Because Ashby is a reliever, he always works out of the stretch, so he doesn't have quite as many herks, jerks or oscillations as famously wacky pitchers like Luis Tiant or Johnny Cueto. He's also developed a fast-paced delivery that helps him create more velocity. All of that makes it easy to miss just how idiosyncratic and bendy the motion is. You and I have already seen through that, though. We've seen how long the ball is behind his head, and how late he bends so much to the right as he whips the ball around and cuts it loose. 

All that deception is why Ashby's stuff looks grosser (and has a greater effect) on batters than pitches with similar raw traits. It was true all year, and all last year, too. It's been especially true this fall, though, for a simple reason: he's gone even more extreme.

Compare that screenshot from midseason to this one, from the NLDS.

The difference isn't huge—not like between Matsui and Ashby, to be sure—but it's there. He's creating even more tilt, moving faster but bending more. As a result, in practical terms, his arm slot is higher. Postseason adrenaline is unlocking a new level of extreme mobility for him. 

You can see this in the data, as well as the pictures. Ashby's (nominal) arm angle is up this month:

As a result, he's getting more carry on his sinker, and he's gotten some swings underneath it, even though it's still very much a two-seamer and not a Matsui-style rise-ball.

Just as importantly, his changeup has found some extra arm-side run, thanks (again) the minute mechanical change. That gives it more separation from his sinker. Ashby has said many times that his changeup is his favorite pitch, but for much of his career, it hasn't been a prominent part of his arsenal. Even throughout this year, it wasn't a major factor. That's changed this month.

Ashby's changeup, with its own kick of added October spice, is humming in at 93 miles per hour. It's coming at hitters with six inches of vertical separation from his sinker and two inches of horizontal separation, in addition to 5-6 MPH of velocity differential. That pitch has allowed him to dominate right-handed batters as well as lefties, facilitating his huge workload.

The delivery Ashby has fully unlocked this month is one of the most impressive athletic movements anywhere in the sport. It's a testament to his incredible balance between strength and flexibility. It's a matter of talent, because the ability to move the way he does requires the baseball gods to bless you with lots of that. It's also a matter of conditioning and intelligent self-design, though. Ashby doesn't look like one of the best athletes in the sport, but he is. The proof has been all over your screen all month. 

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