When the A’s re-signed Mike Fiers to a one-year deal this offseason, they did so with the expectation of him being a workhorse in their rotation. That’s been the standout quality he’s brought since joining the club, making 53 starts from 2018-20 and going 26-9 with a 4.00 ERA in 296 2/3 innings over that stretch.

A lumbar strain forced Fiers to the sidelines for the start of the 2021 campaign. Reinstated from the 10-day injured list in a period when A’s starters entered Tuesday going 10-1 with a 2.92 ERA over the past 14 games, Fiers will be pitching out of the bullpen for the time being.

“It hurts,” Fiers said. “But at the same time, in the position we’re in, I want to do anything that is going to help this team. It’s definitely different after starting for so many years.”

Fiers’ injury in Spring Training opened the door for left-hander Cole Irvin to essentially audition for a rotation spot. With a strong showing in Cactus League play, Irvin pitched himself on the Opening Day rotation. Now 2-3 with a 3.86 ERA, including an 0.79 ERA over his past two outings, Irvin has done enough to keep his role as a starter. according to manager Bob Melvin.

“Mike is starting out in the bullpen. It’s what we have right now,” Melvin said. “We’ll try to keep him stretched out. I don’t know how long it’ll stay like this, but that’s where we are right now. Cole has pitched well, and right now, we’re going with five starters.”

In 19 career relief appearances, Fiers has a 5.40 ERA in 35 innings. His last relief appearance came on Sept. 28, 2018. Those bullpen outings have been sporadic over the course of his 10 seasons in the big leagues. Knowing he’ll be a reliever in the immediate future, Fiers now has a better idea of what to expect, and he will look to develop a routine that better suits him in that role.

“I’m sure Bob is not just going to throw me into these intense situations in a game. That’s going to go to our normal guys,” Fiers said. “I just know I’m in the bullpen. Whenever that phone rings and my name is called, I’m going to get ready to pitch and try to get outs.

“Going into a season, you’re going to need more than five starters. I don’t think there’s one team that has kept five starters for a whole year. We need everybody. I just have to be ready.”