Pirates Place Relief Pitcher on Injured List Before White Sox Game
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CHICAGO — The Pittsburgh Pirates can't seem to avoid injuries and this one has hit their bullpen.
The Pirates placed right-handed pitcher Isaac Mattson on the 15-day injured list with right hip impingement ahead of the series opener vs. the Chicago White Sox at Rate Field on Sept. 8, but retroactive to Sept. 6.
Pittsburgh recalled left-handed relief pitcher Brandon Eisert from Triple-A Indianapolis, who will take Mattson's place in the bullpen.
It's the second injury in the Pirates' bullpen in a week, as right-handed pitcher Kirby Yates is on the 15-day injured list with right shoulder impingement.
Mattson Struggling in 2026
There weren't many better pitchers in the Pirates' bullpen in 2025 than Mattson, who found what he needed and succeeded in his first long MLB stint.
Mattson hasn't followed up on that form this season, posting a 5.35 ERA over 38 games and 38.2 innings pitched, 36 strikeouts to 18 walks, a .282 batting average allowed (BAA) and a 1.60 WHIP.
He has bounced between Pittsburgh and Indianapolis five times, doing so three times since Aug. 1.
Mattson had a strong start to 2026, a 1.13 ERA through his first 13 appearances, but after giving up five runs against the St. Louis Cardinals at PNC Park on April 30, a 10-5 loss, he's been far less effective, with an 8.34 ERA over his last 22 outings.
He's struggled in many different areas, with opposing hitters posting a high hard-hit rate (52.1%) and barrel rate (12.4%), which would rank him among the worst pitchers in baseball if he were qualified.
His last outing vs. the Los Angeles Angels at PNC Park on Sept. 5 also didn't go well, giving up three runs in his second inning of work in the 6-1 defeat.
Mattson can come off the injured list on Sept. 21, so he could return for the final two series of the season.
How the Pirates Bullpen Looks Before White Sox Series
The Pirates have 10 pitchers in their bullpen, with one fewer starter due to Mitch Keller's season-ending injury and an extra arm with the expanded rosters in September.
Pittsburgh has seven right-handed pitchers in Lake Bachar, Khristian Curtis, Wilber Dotel, Camilo Doval, Carmen Mlodzinski, Yohan Ramírez and Luke Weaver, plus left-handed pitchers in Eisert, Mason Montgomery and Gregory Soto.
Bachar will likely start the bullpen game, scheduled for the next contest vs. the White Sox on Sept. 9, and Curtis, Dotel, Mlodzinski, plus Ramírez are all middle-relief options after him.
Doval and Weaver, plus Eisert and Soto, can all throw an inning if called upon and Montgomery has been excellent in the closer role.
The Pirates need a big series from their bullpen, as they try and make a late run at the postseason.
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Dominic writes for Pittsburgh Pirates On SI, Pittsburgh Panthers Pn SI and also, Pittsburgh Steelers On SI. A Pittsburgh native, Dominic grew up watching Pittsburgh Sports and wrote for The Pitt News as an undergraduate at the University of Pittsburgh, covering Pitt Athletics. He would write for Pittsburgh Sports Now after college and has years of experience covering sports across Pittsburgh.