The Boston Red Sox have made quite a few improvements to their bullpen this year. The offseason addition of Aroldis Chapman consistently locking down the ninth inning, as well as a step up from Greg Weissert and the return of Garrett Whitlock, has Boston’s fans feeling much better about the bullpen. But one pitcher in particular has taken that next step.

Justin Slaten has been a force late in games this season. He posted a 2.93 ERA last season in 44 appearances as a Rule 5 Draft pick, racking up 58 strikeouts to only nine walks, which excited fans about his future. His numbers up to this point don’t wow (3.48 ERA in 10.1 IP) due to one blow-up performance on March 31 against the Orioles, during which he allowed all four of his earned runs this season without recording an out. Remove that one bad outing, he’s only allowed two hits, one unintentional walk, and struck out nine in eleven games.

Wel, that was until Thursday night against the Blue Jays when he allowed the go-ahead three-run homer to Vladimir Guerrero Jr. His ERA is now up to an unsightly 5.56, but his WHIP (1.15), H/9 (6.4) and HR/9 (0.8) remain respectable.

There was some chatter during the offseason and spring training about whether he would own the closer role to start the season. Although Aroldis Chapman ultimately won the job, Slaten has already gotten a few chances to close games and has largely looked the part. He has grabbed three saves so far, Chapman has four.

Justin Slaten has mostly dominated in the late innings for the Red Sox

One particular pitch has caught the eye of Red Sox nation: his curveball. Last season, it was his least used pitch at only 8.4%, but this season its usage has jumped to 19.6%. It isn’t that he’s using it more though, it’s the fact it has become his go-to put-away pitch. He is using it 45% of the time in two-strike counts, up from 17.2% last season. Up until Thursday night, he had yet to allow a hit off of it and has gotten three of his nine strikeouts with the curveball, the most of his four pitches.

Although Alex Cora seems content with Chapman holding down the ninth for the moment, it is good to see there’s another trustworthy pitcher back there if Chapman needs a rest or starts to fall off. The emergence of the righty might also quell any thoughts of back-end bullpen help once the deadline rolls around.

Slaten is also giving a very strong audition for next season’s closer role. Chapman is only on a one-year deal, meaning the ninth-inning spot is open again for next season. It wouldn’t be surprising to see Slaten in the role next year assuming he can limit the blowup outings and become even more trustworthy.