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Can DL Hall Remain In The Starting Rotation?

Breaking down some adjustments the Brewers' starter needs to make

One of the major storylines so far this season has been the successful transitions of former relievers into starting pitchers, with pitchers such as Garrett Crochet and Jordan Hicks experiencing success in new roles in their team’s starting rotations. A pitcher who has had a rockier transition from the bullpen to the rotation has been DL Hall of the Milwaukee Brewers.

Acquired as one of the centerpieces of the Corbin Burnes trade last offseason, the Brewers had a vision for Hall. With high strikeout rates throughout his career, the Brewers believed he had the potential to become an impact starter. The results have not translated, as Hall produced a 15.5% strikeout rate and 11.9% walk rate over 16.1 innings pitched this season before being placed on the injured list with a knee injury on April 21st.

While DL Hall has the ceiling to be a key member of the Brewers’ starting rotation, a quick look into his pitch arsenal and approach leaves a few things to be desired. With some adjustments to his four-seam fastball and an addition of a new pitch to his arsenal, DL Hall can recapture his potential as an impact starting pitcher for the Milwaukee Brewers.

 

Overview

Hall’s pitch arsenal predominantly consists of four pitches: a four-seam fastball, a changeup, a curveball, and a slider. Hall primarily uses the fastball, curveball, and changeup to right-handed hitters (utilizing the slider only 5.8% of the time) and becomes a fastball-slider pitcher when facing left-handed hitters (utilizing the curveball only 4.2% of the time and not throwing changeups to same handedness hitters). According to PLV, Hall’s four-seam fastball and curveball grade out as above the league median, while the changeup and slider shapes are well below the league media. FanGraphs’s Stuff+ rates all of the pitches in Hall’s arsenal as below league average.

DL Hall: Statistics (2022-24)

Throughout his minor league career Hall has been a strikeout machine, striking out at least 32% of opposing hitters he faced at each level of the minors. Upon promotion to the majors in 2022, Hall continued to strikeout opposing hitters at an above-average rate, with strikeout rates of 29.7% in 2022 and 28.4% in 2023 out of the Orioles’ bullpen. Upon being acquired by Milwaukee this past offseason, there was optimism that Hall would continue to produce high strikeout totals as a major league starting pitcher, cementing a role in the starting rotation for years to come. These results have not translated to success as a starting pitcher, as Hall produced a 15.5% strikeout rate and 11.9% walk rate over 16.1 innings pitched this season before being placed on the injured list with a knee injury on April 21st. In my opinion, most of this decline in performance can be attributed to a decrease in the quality of his four-seam velocity, with a decrease in velocity and location issues with the offering resulting in hitters improving their performance against the pitch this season.

 

Adjustment #1: Fastball Velocity

A major reason why Hall has struggled to adjust to a role in the starting rotation has been due to a decline in his four-seam fastball velocity this season. Previously displaying a four-seamer that sat above 95 mph and graded as a 70/70 pitch as a prospect, Hall’s four-seam fastball has sat around 92 mph this season, resulting in the pitch generating less swing-and-miss and opposing hitters producing more hard contact against the offering.

DL Hall: Four-Seam Fastball Velocity (2022-24)

With an induced vertical break of 12.3 inches on the offering, Hall’s four-seam fastball sits in the “dead zone” which causes the pitch to appear flat to the hitter, making the offering easier to square up. To mitigate the negative effects of having a dead zone fastball, pitchers either need to improve the induced vertical break they generate on the offering or throw the pitch at a high velocity so the movement profile of the pitch has diminished importance. During the past two seasons, Hall has taken the latter approach, sitting above 95 mph with the offering which allowed for the pitch to still generate swing-and-miss against opposing hitters with a 24.6% whiff rate in 2022, and a 30.2% whiff rate in 2023. So far this season, Hall lost over three mph of average velocity on the four-seam fastball, causing the offering to truly perform like a dead zone fastball, with the pitch only producing a 10.5% whiff rate in 2024.

At first glance, I figured that this drop in velocity was likely due to the change in role for Hall this season. Starting pitchers often sit further away from their maximum velocity than relievers, as relief pitchers typically give “maximum effort” since they have much fewer hitters to face in a given outing than a starting pitcher, therefore Hall probably saw a decrease in velocity since he was trying to pitch more innings. Upon closer analysis, it appears that Hall’s maximum velocity on his four-seam fastball has decreased significantly from 2023, as the pitch is now maxing out at 94.6 mph compared to the 99.0 mph that Hall touched last season. This indicates that the decline in average velocity is not due to Hall pitching away from his “maximum effort”, but rather due to a general reduction in velocity.¬†While the cause for Hall’s knee injury was attempting to field a bunt single, I am curious as to whether Hall was already injured before he was placed on the injured list as this decline in velocity is quite notable.

In his first rehab start since the knee injury on Sunday, Hall was sitting at 94 mph with his four-seam fastball and topping out at 95 mph. This is an encouraging sign of Hall’s recovery, however, he will still need to increase the fastball velocity by a few ticks to get back to the level he was at last season. Placing an emphasis on getting healthy and improving the velocity on his four-seam fastball should be Hall’s top priority, as the effectiveness of the offering serves as the foundation for the rest of his pitch arsenal.

 

Adjustment #2: Fastball Location

Another reason why Hall has struggled to adjust to a role in the starting rotation has been due to the sub-optimal locations of his four-seam fastball. Despite not having an outlier vertical approach angle, Hall has been able to generate swing-and-miss at the top of the strike zone because his fastball exhibited plus velocity and an adjusted vertical approach angle that was above league average. To generate more swing-and-miss on his four-seamer, Hall has to regain his ability to consistently locate the pitch up in the zone.

As shown by the heat maps above, Hall was able to consistently locate his four-seam fastball at the top of the zone over the past two seasons, which allowed him to generate swing-and-miss as hitters would frequently swing under the offering. So far this season, Hall has been locating his four-seamer lower than he has in the past, which has resulted in the pitch being located in spots that will allow a lot of hard contact, with opposing hitters generating a 43.6% hard-hit rate against the pitch this season. Since the pitch is still located in the upper part of the zone, location metrics such as PLVLoc+ may indicate that the pitch’s location is still above league average. However, due to the shape of his fastball, Hall needs to locate the pitch up and above the zone to be effective which he has not been able to accomplish this season.

Locating a dead zone fastball down the middle of the plate is not a recipe for success, and the sub-optimal location of the four-seamer has had just as large an impact on the decreased effectiveness of the pitch as the decline in velocity has. If Hall was previously injured before he experienced his knee strain in April, then it is possible that a nagging injury could have interfered with his delivery, in turn diminishing his ability to command his fastball. In addition to improving the velocity on the four-seam fastball, Hall needs to focus on locating his fastball up-in-the-zone more frequently to reach his ceiling as a starting pitcher moving forward.

 

Adjustment #3: Adding a Sinker and/or Cutter

In addition to improving the velocity and command of his four-seam fastball, Hall could also benefit from adding a sinker and/or a cutter to his pitch arsenal. As mentioned earlier, two ways to improve a dead zone fastball are to either increase the induced vertical break or the velocity of the pitch. A third way to improve a dead zone fastball is for a pitcher to throw multiple fastballs within their pitch arsenal, creating deception for opposing hitters which allows for the four-seamer to “play up”. Given the struggles he has experienced against left-handed hitters, a sinker appears to be the most logical pitch to add to his pitch arsenal, however, a cutter would also make sense if Hall wanted to add a pitch that would be effective against right-handed hitters.

DL Hall: Career Platoon Splits

When analyzing Hall’s platoon splits, it appears that he is more effective at generating strikeouts against right-handed hitters, while he is more effective at preventing walks against left-handed hitters, resulting in his K-BB% against each handedness to equal roughly the same total. In addition, Hall allows a lower wOBA to left-handed hitters than right-handed hitters. Some of this difference can be attributed to a small sample size, as Hall has only faced 69 left-handed hitters in his career, but it provides some insight into what pitches Hall can add to his arsenal to improve his overall results

Against left-handed hitters, Hall needs to generate more strikeouts, and adding an offering that can either generate swing-and-miss or allow another one of his pitches to “play up” appears to be the best way forward. In my opinion, adding a sinker would be the best way to accomplish this objective as it would allow Hall to become a sinker-slider pitcher to left-handed hitters, allowing the fastball to “play up” by utilizing the offering when he’s ahead in the count to generate swing-and-miss. Currently, Hall frequently utilizes the four-seamer to left-handed hitters (62% usage) which has likely caused opposing hitters to sit on the offering, limiting the amount of swing-and-miss it generates. By adding a second fastball to his arsenal, opposing hitters will need to prepare for two fastballs instead of one, allowing Hall to utilize the four-seamer to generate swing-and-miss when hitters are expecting a sinker.

Against right-handed hitters, Hall needs to generate more weak contact to lower his wOBA allowed to the opposite handedness. In my opinion, adding a cutter would be the best way to accomplish this objective as it would allow Hall to have a pitch in his arsenal that can run inside on a right-handed hitter, creating weak contact by missing barrels. Similar to the hypothetical sinker, the presence of the cutter would cause hitters to sit on two fastballs instead of one, allowing Hall to utilize the four-seamer to generate swing-and-miss when hitters are expecting a cutter.

Adding a new pitch is difficult and Hall should place a priority on regaining his fastball velocity and command before focusing on adding a new pitch to his arsenal. However, with the addition of a sinker and/or cutter to his pitch arsenal, Hall can take the next step as a starting pitcher with an arsenal sufficient for facing both right and left-handed hitters.

 

Concluding Thoughts

While DL Hall has the ceiling to be a key member of the Milwaukee Brewers‘ starting rotation, he needs to make a few adjustments to his pitch arsenal to realize his full potential. While the velocity decline and command issues of his four-seam fastball are concerning, Hall can recapture his potential if he is able to improve in these areas upon returning from injury and the addition of a sinker and/or cutter to his arsenal will help his four-seamer “play up”, improving his overall production.

In my opinion, Hall should get at least a couple of chances to start upon returning from the injured list, as I believe he should get a chance to show how he can perform as a starting pitcher when healthy. If the transition to the rotation still doesn’t appear to be viable after making these adjustments then Hall projects to be an above-average reliever, especially if he regains his velocity and can pitch at “maximum effort”.

In conclusion, I believe that DL Hall will be an important piece of the Milwaukee Brewers‘ pitching staff moving forward, and whether or not he will be able to remain in the starting rotation will largely depend on his ability to regain his velocity and command of his four-seam fastball.

 

Feature image by Michael Packard (@CollectingPack on Twitter) / Photo by Keith Gillett/ Icon Sportswire

Adam Salorio

Adam Salorio is a Going Deep Writer at Pitcher List, and a lifelong Boston Red Sox fan. When he's not talking about or researching baseball, you can probably catch him at a Bruce Springsteen concert.

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