CHICAGO — The Orioles have another injury in their starting rotation. This time, it’s right-hander Dean Kremer headed to the 15-day injured list.

Kremer was diagnosed with a right triceps strain, the Orioles said, and the injured list placement is retroactive to Tuesday. Kremer pitched Monday against the St. Louis Cardinals and allowed five earned runs in four innings. That’s when Kremer first felt the triceps discomfort, manager Brandon Hyde said. Kremer was scheduled to pitch Saturday against the Chicago White Sox.

The Orioles also optioned right-hander Jonathan Heasley, who was called up Thursday to replace the injured John Means. Heasley allowed four runs in the ninth inning of the series opener at Guaranteed Rate Field.

The back-to-back days with injured list designations for starting pitchers bring Baltimore’s season total to five starting pitchers missing time through ailments. The Orioles have largely avoided injuries in recent years; in 2023, they had the fifth-fewest combined days lost to injury in the major leagues, according to the Associated Press.

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“We stayed as healthy as we possibly could,” Hyde said. “Give a lot of credit to a lot of people for that. These things are going to happen, so it’s a little bit, ‘Next guy up.’ I think our guys are dealing with it fine.”

Hyde said Means will seek a second opinion on his forearm strain. Means has already undergone Tommy John elbow reconstruction surgery and faced a lengthy road back to the mound.

To replace Heasley and Kremer for the time being, Baltimore promoted right-hander Dillon Tate and left-hander Nick Vespi. Tate was optioned April 29 after pitching 12 2/3 innings this year; he did well in those innings, too, holding a 2.84 ERA. This is the third time Vespi has been in the majors. He served as the 27th man for a doubleheader this week and pitched a scoreless frame.

“I’m comfortable up here,” Vespi said. “Obviously, there’s a learning curve, and I think everyone learns as they go. Doesn’t matter if you’re a one-year big leaguer or a 10-year big leaguer. The game’s always evolving.”

Baltimore’s starting rotation has been in flux for some time now. Means was placed on the 15-day injured list Thursday. Right-hander Tyler Wells is beginning to throw in Florida as he recovers from elbow discomfort. Kyle Bradish and Grayson Rodriguez also spent time on the injured list.

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There is depth, however, and left-hander Cole Irvin will be one of the figures counted upon in the absence of Kremer and Means. Irvin moved briefly into the bullpen once Rodriguez returned, but he has performed well as a starter this season too.

The Orioles could turn to right-hander Albert Suárez to fill Kremer’s gap in the rotation Saturday. Hyde said the Orioles are discussing which direction they will go. One alternative could be to call up left-hander Cade Povich, a prospect with Triple-A Norfolk who holds a 2.08 ERA this year. Povich would be on regular rest Saturday.

“It’s a long year,” Irvin said. “Injuries are going to come and go. When they happen is when they happen. You can’t predict these things and it’s unfortunate we are down two guys this week, but at the end of the day we still have a job to do. We still have a goal in mind. At some point, I know we’ll be healthy again, and so, just hold the torch until we need to pass it.”

Hyde said he hopes Kremer’s injury will have a timetable similar to the one Rodriguez recently recovered from. Rodriguez missed just over two weeks and didn’t require a rehab start prior to returning.

“This isn’t uncommon right now, everywhere,” Hyde said. “You gotta be able to make adjustments and deal with some adversity. Pitching hiccups are going to happen, and injuries are going to happen. That’s why you hopefully create as much depth as you possibly can.”