The Yankees cut bullpen acquisition Enyel De Los Santos just two weeks after they acquired him from the San Diego Padres at the trade deadline. He now pitches for the Chicago White Sox, a team that put up seven runs against De Los Santos before claiming him off waivers.
The Yankees were left scratching their heads, wondering how his underlying metrics imploded the second he came to the Bronx. However, he’s not the only relief arm struggling to find a place in his new home.
Mark Leiter Jr.’s Unexpected Struggles with the Yankees
Mark Leiter Jr., 33, is only a free agent in 2027, so he’s expected to remain with the Yankees for the next two seasons, barring a massive regression in production. The Yankees are likely questioning what exactly happened to him since his move from Chicago to New York, where his ERA ballooned from 4.21 to a staggering 5.79.
The Yankees acquired him for his solid xERA and underlying metrics, but something is seriously wrong with Leiter’s efficiency over the past few weeks. With the Bombers, he’s pitched 14 innings and has seen a significant regression, including a 13% drop in ground ball rate and an increase to 2.57 home runs per nine innings, up from just 0.5 with Chicago. Even his walks per nine have increased by about 6%. The Yankees are trying to figure out the root cause of these efficiency issues.
Shift in Pitch Mix and Its Impact
Leiter has some of the best swing-and-miss stuff on the team, ranking in the 94th percentile in chase rate, 98th percentile in whiff rate, and 95th percentile in strikeout rate. These metrics should produce far better results, but teams are crushing his sinker, which is generating a .373 batting average and a .552 slugging rate. It’s like Aaron Judge taking batting practice against his sinker every time he throws it—that’s the level of production opposing batters are getting from it.
The Yankees have altered his pitch mix significantly, asking him to throw his split-finger fastball more frequently and lean more on his curveball. He’s throwing his sinker 7% less than before, which is intriguing given its poor results and recent inefficiency. However, his sweeper usage has increased significantly, indicating that pitching coach Matt Blake is experimenting with new combinations.
The Sinker Dilemma
In August, Leiter’s sinker produced a .667 batting average over 75 pitches, which is highly problematic. Meanwhile, his split-finger fastball produced a .130 batting average, suggesting that the Yankees might eliminate his sinker altogether in favor of breaking balls and increased reliance on his split-finger fastball—a trend that has already started in September.
The challenge for Leiter is that he lacks a primary fastball without his sinker, with his cutter, at 89.1 mph, being the next fastest pitch. However, his cutter isn’t a major component of his pitch mix. The Yankees may have to rely more heavily on his breaking stuff, which is still effective, given his off-speed run value ranks in the 96th percentile.
Urgent Need for Adjustments
Given that Leiter has allowed an earned run in six of his last nine appearances, it is clear the Yankees need to make changes now before things spiral further out of control. While he managed to escape a bases-loaded jam against the Texas Rangers on Wednesday night, he had given up an earned run in three straight outings before that, despite recording substantial strikeouts.
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The issue with Leiter is that while he’s striking out many batters, the contact made against his pitches often results in significant damage. A lack of velocity can contribute to this problem, so the Yankees have their work cut out for them in trying to revitalize his season following the acquisition.