At the trade deadline in late July, the Yankees made three key acquisitions aimed at bolstering their roster for a deep playoff run. While the addition of Jazz Chisholm has proven to be a major success, particularly with his contributions at third base and on offense, their bullpen acquisitions have been less fortunate.
A Bullpen Bust: Enyel De Los Santos
One of the two bullpen arms acquired, Enyel De Los Santos, has already been released after several months of underperformance. The move highlighted the challenges the Yankees have faced in shoring up their relief pitching this season.
Mark Leiter Jr.: Struggles and Potential
The other bullpen acquisition, Mark Leiter Jr., hasn’t been much better overall, but he’s starting to show signs of improvement. Before being traded from the Chicago Cubs, Leiter had tossed 36.1 innings with a 4.21 ERA, but his underlying metrics suggested untapped potential. The Yankees hoped to capitalize on these numbers, but Leiter’s performance since joining the team has been disappointing.
In 19 innings with the Yankees, Leiter has posted a 5.68 ERA, allowing 2.84 runs per nine innings—numbers that are unsustainable for a reliable reliever. Despite these struggles, his strikeout rate has remained impressive, with 12.79 strikeouts per nine innings. However, his ground ball percentage has plummeted by over 10% since the trade, contributing to his difficulties on the mound.
Analyzing the Underlying Metrics
Despite the overall decline, Leiter’s advanced metrics remain promising. He ranks in the 96th percentile for chase rate, 97th percentile for whiff rate, and 95th percentile for strikeout rate. Clearly, Leiter has the tools to be an asset for the Yankees, but his main challenge lies in pitch location, which has resulted in hard contact from opposing hitters.
One glaring issue has been his sinker, which has become a liability. This pitch has allowed a .394 batting average and a .620 slugging rate, while averaging just 91.5 mph. In contrast, his split-finger fastball and curveball have been far more effective, showing elite performance levels. The Yankees have noticed this and are making adjustments to his pitch usage.
The Yankees are Adjusting the Approach: Reducing the Sinker
Since joining the Yankees, Leiter’s sinker usage has significantly decreased. In September, he threw his sinker just 13.7% of the time, compared to 31.9% in August. Instead, the Yankees have encouraged him to rely more on his split-finger fastball and curveball, which have been dominant.
In a recent outing against the Oakland Athletics, Leiter threw 27 pitches, only four of which were sinkers. Instead, he leaned heavily on his split-finger fastball (11 pitches) and his curveball (seven pitches), while mixing in a few cutters and sweepers. The result? Three strikeouts in two innings, where he was nearly untouchable. This shift in approach may prove to be the key to unlocking Leiter’s full potential.
Maximizing Leiter’s Potential
At 33 years old, the Yankees have control over Leiter until the 2027 free agency, giving them plenty of time to optimize his performance. Though not a high-velocity pitcher, Leiter’s ability to generate movement on his pitches makes him a valuable asset if used correctly. The Yankees’ recent adjustments to his pitch mix may be the key to maximizing his effectiveness and transforming him into a reliable bullpen arm.
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A Work in Progress
While the Yankees’ bullpen acquisitions have had mixed results, there’s still hope for Mark Leiter Jr. to turn things around. By reducing his reliance on the sinker and focusing on his best pitches, the Yankees may have found a recipe for success. With the postseason approaching, the team will need Leiter to continue improving if they hope to make a deep playoff run.