Mark Leiter Jr. was not considered a big-time reliever entering the 2025 season after having a tough go of it with the Yankees during the 2024 regular season. He was so ineffective after the trade deadline that they opted to leave him off of their playoff roster entirely until Ian Hamilton suffered an injury that knocked him out for the remaining ALCS and World Series games.
This accidental opportunity would give Leiter some new life, as he was effective and reliable, weaving into and out of trouble in some big spots during their pennant run.
Still, the expectation was that he would be nothing more than a solid reliever for lower-leverage situations, and after surrendering a back-breaking grand slam against Arizona early in the season, pessimism only grew louder.
After that tough outing, Mark Leiter Jr. has been brilliant, and the Yankees have another high-leverage weapon on their hands, who is another tool in Aaron Boone’s loaded bullpen.
How Mark Leiter Jr. Has Become a Big Part of the Yankees’ Bullpen
The Yankees have not shied away from using Mark Leiter Jr. in big spots despite his early struggles, blowing some big games in 2024 and having his own set of scuffles in 2025.
It’s easy to simply write off a reliever who isn’t getting it done in high leverage, and the Yankees definitely had a rotating door of set-up men before Devin Williams stabilized and Jonathan Loaisiga returned from the IL.
Some of his poor outings have been a result of really poor luck; he was tagged with a loss against the Rays despite an Anthony Volpe error resulting in a run scoring without recording an out on a routine double play ball.
He also gave up a plethora of soft hits with poor defense behind him in Cleveland, a game he took the loss, although he didn’t pitch all that poorly.
When you isolate when Mark Leiter Jr. can control, his 29.1% K-BB% leads all qualified relievers on the Yankees and is ninth in the entire sport among relievers.
He is a strikeout machine who has cut down his HR/9 from 1.24 last year to 0.46 this year, as his stuff has improved, especially when you evaluate his sinker.
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He is throwing his sinker much harder than he did last season and is getting more ride on it, setting up his splitter and curveball to generate whiffs and soft contact.
Mark Leiter Jr. has gone from having a bad fastball that he had to avoid using in the postseason to having a heater that he can throw past some hitters and generate soft contact with.
Hitters have to respect the 94-95 MPH heater he can rear back and throw, while also being ready to handle a splitter that has ridiculous whiff rates.
We’re also seeing him freeze more hitters as well, with his Called Strike% increasing from 15.9% to 19.4%, and any time a pitcher gets a called strike, that’s a win.
Among MLB relievers, Mark Leiter Jr. is 13th in fWAR (0.7), and if he keeps this up, he’ll be an effective set-up man in a bullpen that’s grown to have a litany of strikeout arms.