Red Sox's Most Slept-On Pitcher Just Added New Weapon to Arsenal

The Boston Red Sox can afford to come into the season with high expectations for righty hurler Justin Slaten.

Predicting which pitchers will have successful seasons, especially out of the bullpen, is a lot more complex than simply looking at last year's statistics. Slaten wasn't anywhere near one of the Red Sox's best relievers if you go by his 4.24 ERA and 25 strikeouts in 34 innings.

But those who have seen a lot of baseball can tell there are some special qualities about Slaten's pitch mix. And on Wednesday, he showcased an entirely new offering that has the potential to make his arsenal even tougher to crack.

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Slaten's new splitter could be game-changer

Sep 26, 2025; Boston, Massachusetts, USA; Boston Red Sox relief pitcher Justin Slaten (63) pitches against the Detroit Tigers during the fourth inning at Fenway Park. Mandatory Credit: Eric Canha-Imagn Images | Eric Canha-Imagn Images

For the first time in game action, Slaten busted out a splitter on Wednesday in his scoreless inning against the Minnesota Twins in spring training.

Per Thomas Nestico of TJStats, Slaten threw the pitch twice, and it graded out with a 104 TJStuff+ (100 is average). It should be a pitch the righty can effectively tunnel off his four-seam fastball against right-handed batters.

Justin Slaten looks to be throwing a new splitter!

Slaten is one of my favourite relievers thanks to his extreme N-S arsenal and ability to mitigate damage, and now he has a new pitch to help deal with LHH. It's deviation from his fastball helps it grade out very well! pic.twitter.com/zS48FRK5vH
— Thomas Nestico (@TJStats) February 25, 2026

Slaten has thrown four pitches in both of his seasons in the majors, and all of them have been filthy at times. His fastball and cutter can both be bowling balls, and his curveball is a hammer when it's playing well off the trajectory of that fastball.

But add in his sweeper, and you have four pitches, none of which break away from left-handed batters. The splitter is a natural remedy to that slight problem.

Slaten also isn't the only Red Sox pitcher experimenting with the pitch this year. Ace Garrett Crochet spent the offseason working on a splitter while training at Vanderbilt, and he'll get the chance to show it off for the first time in a game on Thursday.

Boston's bullpen was anchored by closer Aroldis Chapman and Garrett Whitlock last season. But Slaten was supposed to be in that mix as one of the most trusted guys, and because he had some rough patches and a prolonged stint on the injured list, he may have become something of a forgotten man.

If that splitter works as intended, however, he could be one of the most dominant arms in any bullpen.