New adjustment could help Luis Perdomo carve out role in Brewers bullpen

With usual high-leverage arms Josh Hader and Trevor Gott unavailable for Wednesday’s series finale against the San Diego Padres, the Brewers had to turn to an unlikely source to work the middle innings ahead of Brad Boxberger and the temporarily-promoted Devin Williams.

That source turned out to be Luis Perdomo, who entered in the sixth inning after Aaron Ashby allowed a two-out single. He promptly induced a ground ball to the shortstop to end the frame. After the Brewers scored two runs, Perdomo returned to the mound to throw a scoreless seventh with help from a web gem by Kolten Wong.

The right-hander recorded all four of his outs on ground balls. That should come as no surprise, as the former Padre has always induced grounders at a strong clip. In five seasons out west, he posted a 57.3% ground ball rate.

However, just because he kept the ball on the ground did not mean he was inducing weak contact. On the contrary, Perdomo regularly posted poor hard-hit numbers as a Padre. In three of those five seasons, he allowed an average exit velocity of 90 mph or higher. Most of that damage came against his sinker.

In a limited sample, Perdomo has started his Brewers career with improved marks in both of these areas. Not only has he posted a gaudy 73.3% ground ball rate, but he also has limited opponents to an 87.1 mph average exit velocity, which is below the league average of 88.8 mph.

Neither of those numbers means much in a sample of 8.1 innings, however. Perdomo has done a better job of inducing weak ground balls so far, but that could easily change in a single outing.

At this stage of the season, the adjustments that Perdomo has made on the mound are more noteworthy than the early returns.

His stuff doesn’t look different. Perdomo has lost a tick of velocity since returning from Tommy John surgery, but he still sits in the mid-90s with his sinker. All three of his pitches—sinker, slider and splitter—are moving just like they did before he went under the knife.

However, Perdomo is giving hitters a new look. His release point has shifted noticeably toward third base.

BrooksBaseball

BrooksBaseball

After previously pitching from the middle of the rubber, Perdomo is now pitching from the third-base side of the slab. As such, his horizontal release has shifted by nearly an entire foot. Additionally, he has also lowered his arm slot by a few inches.

This new release point creates a different look for opposing hitters, and it makes the most difference for right-handed swingers. The stills below of Perdomo’s releases from 2019 and 2022 illustrate the change in how hitters perceive the ball out of his hand.

MLBAM

The change in Perdomo’s positioning on the rubber is evident, and his release point is noticeably closer to the batter’s box.

We can use Statcast pitch visualization technology to illustrate further how this appears to the hitter. Pictured below is a simulation of how a right-handed hitter perceives each of these release points.

Baseball Savant

The new release point makes it look to the hitter as if Perdomo is practically on top of them as he releases the ball. This creates a more uncomfortable at-bat from the start, and it doesn’t get much better when you know that you’re about to see one of two pitches: a mid-90s fastball running in on your hands or a slider that appears to start at your head but ends up outside off the plate.

While shifting Perdomo’s positioning on the rubber does increase the risk of some sinkers running inside and hitting batters, it also reduces his likelihood of leaving them over the middle and outer third of the plate. Perdomo’s top goal is to induce ground balls and jam hitters, so pitching inside with his sinker is his best friend.

One might expect that a ground ball pitcher with a high ERA has been hampered by heavy platoon splits. That has not been the case for Perdomo. While left-handed opponents have done more damage (career .834 OPS), right-handers have also had their fair share of success against him (.766).

Despite inducing plenty of ground balls, Perdomo has never been very successful, even when he has the favorable platoon matchup. Delivering the ball closer to third base may help him hit the inside corner more consistently with his sinker. It could also create a more difficult angle for opposing hitters and prevent them from leaning over the plate, making it more difficult to protect against a slider on the outer third.

This change is not guaranteed to work. Behind Perdomo’s shiny ERA and ground ball rate are some unappealing peripherals. He has struck out just one hitter this season, which is the main driver behind his 5.16 FIP. Perdomo has also benefitted from a 93% left-on-base percentage. Even if he can escape more jams than the average pitcher by inducing double plays, that figure will regress.

Maybe the new release point will help Perdomo emerge as a ground ball specialist and weak contact machine against right-handed hitters. Perhaps he won’t progress beyond the below-average numbers he has posted for much of his career. Either way, the shorthanded Brewers bullpen is about to find out what they have in him.

Statistics courtesy of FanGraphs and BrooksBaseball.