DL Hall Made a Key Slider Adjustment Last Summer, and Perhaps Another One This Spring

In the first half of 2023, DL Hall was a pretty good pitcher, but he wasn't at full strength. After coming to spring training with an injury to his lower back that required careful maintenance, he was handled with kid gloves early in the Triple-A season, then sent back to the team's complex in Florida for two months. There, he hardly appeared in competitive games at all. He worked, instead, on getting stronger and building his velocity, and he made a couple of adjustments. When he returned to the highest level of the minors (and eventually to the Baltimore Orioles) in the second half, there were some stark differences.

Now, the new version of Hall is a Brewer, and whereas he pitched in relief only down the stretch last year, he looks likely to be a starter for the Crew in 2024. Thus, we should take a few minutes to be specific about the transformation he underwent last summer, and about what he might already be doing slightly differently under the tutelage of Chris Hook.

First, to lay the groundwork, consider Hall's pitch break chart for the first half of 2023. Here and in the next few images, I've elected to color the data points by velocity, rather than pitch type. You'll see why in a bit, but for now, it should be easy enough to pick out his fastball, changeup, slider, and curveball, based on the shapes of movement suggested by the chart. (The image is from the pitcher's perspective, so a point in the lower right quadrant is a down-breaking offering that is moving away from a lefty batter or in on a righty.)

As you can see, there's some wide velocity variation within Hall's slider mix. He was reaching 90 miles per hour with it at times, but at others, he would soften it to the underside of 85 miles per hour to gain more movement. It was, in those cases, almost a sweeper. The rest of the arsenal is pretty standard: fastball with great life but ordinary x-and-y movement, changeup fading off of it, curveball with mirrored spin and a three-quarter shape.

While he was down in Sarasota, though, Hall made two major changes. Firstly, he changed the grip on his slider, and it radically altered that pitch's movement profile. The spin he imparted on the pitch out of his hand didn't change from the first half to the second.

So we can rule out, with reasonable confidence, the idea that Hall changed his hand position or wrist action on the slider during that interregnum. The change he did make, though, generated a huge change in the actual movement of the pitch.

As I alluded to in noting the sweeper-like movement of some of his slower first-half sliders, Hall was getting a bunch of lift on that offering. He got underneath it a bit, as pitchers will occasionally say, resulting in lots of sweep but little depth. In the second half, after whatever subtle change he made, the same spin out of the hand was producing a truer, but heavier actual break. It still has some horizontal movement (especially compared to his fastball), but it's also moving much more, vertically. The above implies that, but here's his second-half pitch break chart, to verify it.

That's a nasty pitch, especially when it's routinely thrown 87-89 MPH. Importantly, though, Hall threw it that hard in the context of working as a reliever. We can assume that he'll give back a tick on just about everything if he sticks in the rotation this year. Even so, it's going to be a killer offering, given the action on his fastball and the confidence he's gained in his excellent changeup.

Another important change occurred during that time down in Florida, and might be just as important as tweaking the slider. With his back fully healed and some time carved out just to get stronger, Hall moved over toward the first-base side of the rubber, got down the mound better, and improved the consistency of his release extension. Here's where he was releasing the ball in the first half:

And here, after the slide across the mound and the mechanical and strength work, is where he did so in the second half.

As I wrote for Monday, Hall's fastball is dominant not because of its raw movement or its sheer velocity, but because of the interaction between those elements and his release point. Changing that release point--and especially improving his extension--augmented the dynamism of that offering, and his new place on the mound sets up some different things in his approach to hitters, too.

Ok, one last chart before we go. On Sunday, Hall appeared in his first Cactus League game of the spring. Because it was at the only venue in the Cactus League that gives us all access to public Statcast data, it was a treasured opportunity to test something I thought I spotted during Hall's dazzling sim game against a few teammates last Monday. Indeed, among a handful of the same new sliders he showed last year, there was one little outlier worth attending to closely.

Early last year, Hall had a sweepy slider, without much depth. Late last season, he threw a slider with plenty of depth, but little sweep. On Sunday (and in that sim game early last week), he showed both, even if he only threw a sweeper-ish one once Sunday. If he can maintain feel for both of those slider looks and establish a fifth pitch, he could take the next step toward ace status this season.

Many of these changes are ones he made before being traded to the Brewers, but they fit very nicely with the things the Brewers have done to help other pitchers improve in recent years, up to and including this spring. The match between Hall and Hook seems as good as that between marble and Michelangelo. Hall is the best reason to be excited about the Brewers' starting rotation; he just needs to stay healthy enough to take his place in line behind Freddy Peralta.