The Twins continued to tinker with the back end of their bullpen Thursday as they designated righthander Matt Magill for assignment and called up righthander Kohl Stewart from Class AAA Rochester.

Magill posted a 4.45 ERA in 28 games with the Twins this season. That ERA went down in an inning of work Wednesday, but the Mets scored six unearned runs off him, including a 474-foot home run by rookie sensation Pete Alonso.

“He certainly has the stuff to go out there and compete against major league hitters,” manager Rocco Baldelli said, “and I expect to see him out there doing so going forward.”

If Magill is not claimed by another team off waivers, the Twins can assign him to Rochester.

This is the fifth time Stewart, the fourth overall pick in 2013, has been called up this season. He is 5-5 with a 6.28 ERA in 14 appearances (13 starts) at Rochester, compared to 4.15 in four appearances (two starts) with the Twins. He can handle both short and long relief roles for the Twins, who currently are operating with a seven-man bullpen.

“We don’t know exactly how he’s going to make his first appearance back or how it’s going to work,” Baldelli said, “but he’s shown the ability to get the job done regardless of what that role is.”

Magill, righthander Mike Morin and lefthander Adalberto Mejia have all been designated for assignment since Saturday. In addition, lefthanders Gabriel Moya and Andrew Vasquez and infielder Ronald Torreyes are minor leaguers who have been taken off the 40-man roster recently.

A couple of the moves were to make room for others, but the Twins currently have four open spots on their 40-man roster. That’s plenty of room to add new players, and it just so happens to be less than two weeks before the July 31 trade deadline.

“The guys that we took off that were on the back end of our bullpen [and] were out of options,” Twins Chief Baseball Officer Derek Falvey said. “The only way to create the spot was to designate them. We would have loved for each of those guys to still have options so we could have sent them to the minor leagues, that way, we could bring them back.”

Falvey and General Manager Thad Levine continue to discuss potential deals with clubs, and talks should pick up as July 31 nears. While the Twins appear to be exhausting in-house options, they have space for acquisitions.

Scheduled days off

Shortstop Jorge Polanco and left fielder Eddie Rosario were not in the starting lineup Thursday night, but nothing to be too concerned about.

Polanco, who has appeared in a team-leading 90 games, was getting scheduled time off. Baldelli said there were times during the first half that Polanco was scheduled for a break but was needed because other players were banged up.

“This is something that we wanted to make sure we were able to do,” Baldelli said. “and I think he’s going to get some at least semiregular rest when we can start treating him like the other guys on this team that play all of the time.”

Rosario just returned to the lineup Tuesday after recovering from a sprained left ankle, so Baldelli didn’t want to play him continuously yet.

Getting better

Center fielder Byron Buxton was on the field for early running and throwing as he recovered from a concussion he suffered Saturday. The Twins aren’t sure when he will return, but it’s a good sign that he’s able to do some baseball activities.

“Buck had a really nice day,” Baldelli said. “I think if you get a chance to talk to him, you can see that he’s personality-wise, energy-wise doing very well. Feeling a lot better. … It was a good day.”