NEW YORK -- Seeking “something outside the box that may help us in our bullpen effectiveness,” in manager Mickey Callaway’s words, the Mets are moving longtime starter Steven Matz to the bullpen for the remainder of the first half. While Callaway described the move as “temporary,” he hedged multiple times when asked if Matz will return to the rotation after the All-Star break.

“Anything can happen,” Callaway said. “We have a long time until we need a fifth starter, including the four days during the All-Star break, so we’re going to do whatever is necessary for this team to turn the corner and start winning more games.”

The Mets do not need a fifth starter again until July 21, at which point the rotation could look markedly different as the Mets begin selling pieces prior to the July 31 Trade Deadline. If the Mets deal Zack Wheeler or Jason Vargas, or both, they will undoubtedly need to put Matz back in the rotation.

“He’s one of our top five starting pitchers at this point,” Callaway said. “I don’t think this is a knock on him.”

Still, Matz struggled in June, posting a 7.36 ERA in six starts while opposing hitters produced a .300/.380/.558 slash line against him. The last of those outings was a rain-shortened, two-inning outing last Saturday, which played into the Mets’ reasoning to move Matz to the bullpen. Because Matz only threw 27 pitches in that game, the Mets knew he was available to pitch out of the bullpen almost immediately.

A lifelong starter, Matz -- when healthy -- has been a member of the Mets’ rotation since his callup in 2015.

“He’s been healthy for a while now,” Callaway said. “I think those health issues are far behind him. He recovers probably better than any pitcher on our staff now. He works probably harder than anybody. So I think he’ll be able to handle this.”