Mar 27, 2025; Arlington, Texas, USA; Boston Red Sox pitcher Justin Slaten (63) reacts after winning the game in the ninth inning against the Texas Rangers at Globe Life Field. Mandatory Credit: Tim Heitman-Imagn Images Tim Heitman-Imagn Images
There's a new star being born for the Boston Red Sox, and it's high time he gets the shine he deserves.
Second-year relief pitcher Justin Slaten entered 2025 with fairly high expectations, and with good reason. He was excellent as a rookie, after arriving in a trade with the New York Mets, who had just picked him up in the Rule 5 Draft from the Texas Rangers.
There are levels to good as a reliever, though, and early this season, Slaten hasn't just been good--he's been dominant. And soon enough, the Red Sox are going to have to think about making him the full-time closer.
Seven-time All-Star Aroldis Chapman has been the closer all season so far, and he's been great. His only two earned runs allowed have come against the Chicago White Sox, and he's throwing 100 to 102 miles per hour with regularity. But Slaten has already earned the chance to pitch the ninth if it helps with matchups, as was the case Monday when the eighth inning was full of lefties.
At first glance, people might look at Slaten's 4.00 ERA and 0.0 bWAR through eight appearances and ask why this is even a topic of conversation. For that, you have to get into some of the advanced stats, and rest assured, it's worth the digging.
Slaten has a 2.25 FIP, meaning his ERA is grossly inflated thanks to the four earned runs he allowed without recording an out on Mar. 31. He allows 0.55 runners to reach base per inning pitched, and his 1.92 expected ERA is in the 95th percentile of all pitchers.
He's developed a curveball, which he only threw eight percent of the time last season, that simply isn't getting touched, with a .000 batting average against and 55.6 percent whiff rate so far this year. And he already had three very tough pitches to hit, so he's entering new territories of filthiness.
None of this is an insult to Chapman, and for the time being, it makes sense for the Red Sox to continue playing matchups with the two of them. In fact, if Chapman keeps pitching well, it's a good idea to do so all season.
But eventually, Slaten will be the closer of the Red Sox, whether it's in 2025 or 2026. He's too filthy not to be.
