The Yankees bolstered their bullpen on Monday, acquiring right-hander Clay Holmes from the Pirates in exchange for infielders Diego Castillo and Hoy Park.

Holmes has a 4.93 ERA with 44 strikeouts in 42 innings out of the bullpen for Pittsburgh this year, and he owns a a 5.57 ERA over parts of four seasons, all with the Pirates. The 6-foot-5 righty was Pittsburgh’s ninth-round pick in the 2011 Draft and now joins former teammate Jameson Taillon on the Yankees’ pitching staff.

“We feel like he's going to be a guy that is already very tough on righties, but we feel like he has the stuff and the repertoire to go to another place,” Yankees manager Aaron Boone said on Tuesday at Tropicana Field. “We feel like he's having a really strong season, a lot better than his ERA would suggest.

“I think he gives us a really interesting look in our bullpen as a kind of a righty assassin. We feel like there's still room in there for him to continue to grow as a really good reliever in this game.”

Holmes’ calling card is his sinker, which can top 98 mph and averages 95.7 mph, as well as 5.3 inches more drop than the average sinker -- tied with new teammate Zack Britton near the top of the MLB leaderboard. Opponents have batted just .232 and slugged .317 against the pitch this season, with an absurd 87.7% ground-ball rate.

Holmes’ overall ground-ball rate of 72.4% entered Monday as the highest among any pitcher this season (minimum 100 batted balls), which should be an asset at Yankee Stadium. On the other hand, his 13.2% walk rate is also among MLB’s highest, and those free passes have contributed to some blowup outings. Fourteen of Holmes’ 24 runs allowed this season have come in just three games, during which he walked eight of 21 batters faced.

As for Castillo and Park, neither currently ranks on MLB Pipeline’s list of the top 30 Yankees prospects, although Park has enjoyed a big season in 2021. After starting at Double-A Somerset, the 25-year-old South Korea native moved up to Triple-A Scranton/Wilkes-Barre and hit .327/.475/.567 in 48 games there, with 10 home runs, 29 RBIs and eight stolen bases, while playing both middle-infield positions and in the outfield. He also received a brief Major League callup, making his debut off the bench and going 0-for-1 on July 16.

Castillo, 23, has spent 2021 at Double-A Somerset, where he has played second, third and shortstop and batted .277/.345/.504 with 11 homers, 32 RBIs and eight steals in 58 games.