PITTSBURGH — Injuries have plagued the Pittsburgh Pirates, and they've now hurt an important part of their bullpen.The Pirates placed right-handed relief pitcher Kirby Yates on the 15-day injured list, retroactive to Aug. 31, with right shoulder impingement. Pittsburgh also recalled rookie right-handed pitcher Khristian Curtis from Triple-A Indianapolis to fill in for Yates' absence.This is the second roster move the Pirates have made ahead of the series finale vs. the San Francisco Giants at PNC Park on Sept. 3, as they also recalled fellow rookie right-handed Wilber Dotel and optioned left-handed pitcher Evan Sisk to Indianapolis.Pirates Lose Strong Bullpen Option in YatesYates joined the Pirates in a trade at the Aug. 3 deadline from the Los Angeles Angels, with right-handed pitching prospect Kyle Robinson going the other way.He has been one of the best relief pitchers for the Pirates since joining, posting a 2-0 record in 13 appearances, a 2.19 ERA over 12.1 innings pitched, 11 strikeouts to five walks, a .239 batting average allowed and a 1.30 WHIP.Aug 21, 2026; Los Angeles, California, USA; Pittsburgh Pirates pitcher Kirby Yates (54) throws in the sixth inning against the Los Angeles Dodgers at Dodger Stadium. Mandatory Credit: Kirby Lee-Imagn Images | IMAGN IMAGES via Reuters ConnectYates' best moment with the Pirates came against the San Diego Padres at Petco Park on Aug. 24, working out of a bases-loaded jam in the 11th inning, a strikeout on three pitches and a lineout.The Pirates would go on and win that game 3-2 in 12 innings, ending a potential four-game losing streak after suffering a series sweep to the Los Angeles Dodgers at Dodger Stadium, Aug. 21-23.Yates last pitched for the Pirates against the St. Louis Cardinals on Aug. 30, throwing a scoreless sixth inning in the eventual 5-4 win.What the Pirates Bullpen Looks Like NowThe Pirates' bullpen now has seven right-handed pitchers in Lake Bachar, Curtis, Dotel, Camilo Doval, Carmen Mlodzinski, Yohan Ramírez and Luke Weaver, plus three left-handed pitchers in Brandon Eisert, Mason Montgomery and Gregory Soto. Bachar started against the Giants in the Pirates' bullpen game, which replaced Mitch Keller, who is out with a season-ending injury.The Pirates will likely have both Dotel and Curtis pitch against the Giants, with Dotel throwing an inning on Sept. 1 and Curtis throwing 3.1 innings on Aug. 28, with each taking on a bulk role.Pittsburgh should also have Ramírez and Weaver available, plus all three southpaws if they need to against San Francisco.Make sure to visit Pirates OnSI for the latest news, updates, interviews and insight on the Pittsburgh Pirates!Add us as a preferred source on GoogleFollow