OAKLAND -- The A’s expect Ryan Buchter to be a key part of their bullpen, but after a rough start to his season, they felt a trip to the Minor Leagues could do the left-hander some good.

The A’s optioned Buchter to Triple-A Las Vegas and recalled right-hander Ryan Dull before Monday’s series opener against the Rangers at Oakland Coliseum.

Buchter was a key piece of the A’s 2018 run to the postseason as more than just a lefty specialist. Manager Bob Melvin often went to Buchter even against right-handed batters, and he responded well with a 2.75 ERA in 54 appearances in his first season with Oakland.

But in 13 appearances this year, Buchter’s ERA ballooned to 7.04, giving up three runs in his last three outings. Melvin expects Buchter back at some point this year, but for now, he’d like to see the lefty work on some mechanical issues in Las Vegas.

“There are certain guys that either don’t belong here or get sent down because of performance. This is a guy we’re really going to need,” Melvin said. “When he’s on, he’s not just a left-handed bullpen guy, he’s a good one. We just need to get him straightened out a little bit.”

The decision to option Buchter was also due in part to a taxed bullpen. Dull gives the A’s bullpen a fresh arm after relievers had combined to throw 16 innings over the past three games entering Monday night.

Dull owns a 3.81 ERA in five big league seasons, all with the A’s. He earned a spot on the roster for the A’s series-opening trip to Japan after a strong Spring Training, in which he did not allow a run over five outings. His success continued at Triple-A, where he did not allow a run over 9 2/3 innings of relief.

“We’ve been using the fastball and slider a lot,” Dull said of his key to success. “Just being able to move the baseball around a lot. It’s awesome just being back up to help contribute any way I can. I’m ready to do whatever I’m asked to do.”

Buchter’s absence leaves the A’s without a left-handed reliever, joining the Angels as the only two teams currently facing that situation. It’s not ideal while facing the Rangers, a team that is heavy on left-handed hitters, but Melvin said the A’s have enough right-handers with success against lefties to get by.

“You just try to identify the righties that can get the lefties out,” Melvin said. “You have to go with what you think the best mix is at the time.”

Olson hits soft-toss

Matt Olson (right hand surgery) took a big step in his recovery Monday as he hit soft-toss pitches with a regular bat for the first time. He’ll take part in batting practice over the next few days and is set to travel with the A’s during their upcoming road trip, which begins Friday in Toronto.

Melvin said Olson will take batting practice for about a week and a Minor League rehab assignment could come soon after, with a return to the Major Leagues targeted for mid-May.

Anderson not expected to miss time

The A’s appear to have avoided something major with Brett Anderson.

After departing Sunday’s start early with a left ankle sprain, the left-hander was pain-free on Monday. Melvin is optimistic Anderson will be available for his next start, which would come Saturday in Toronto.

“With some of the advanced things they can do now in the training room, I think we got him out of there before it got worse, and they worked on him pretty extensively,” Melvin said. “I’m encouraged that he could potentially make his next start.”