SEATTLE -- The Mariners optioned young right-handed starter Matt Brash to Triple-A Tacoma on Thursday, with the plan to transition him to a bullpen role for the rest of the season.

Seattle manager Scott Servais said the team thinks Brash can best contribute on the big league club from the bullpen this year. He did not commit to Brash relieving long term.

"I definitely think he's a guy that can help us win games this year. I just think the chance to impact our team is probably greatest if he can assimilate to the bullpen and come out and help us there on multiple days in a week versus just one day a week," Servais said.

Brash, who turns 24 next week, was 1-3 with a 7.65 ERA in five starts. He gave up six runs in two innings last Friday against Miami, and Wednesday he lasted just three innings and gave up six hits and four runs in a loss to Houston.

Seattle has not announced who will take Brash's spot in the rotation, but top prospect George Kirby might be the Mariners' best option in the minors.

Along with Brash, the Mariners also placed right-handed reliever Matt Festa on the 15-day injured list with elbow tendinitis. Right-hander Riley O'Brien was recalled and lefty Danny Young was selected from Tacoma.

Seattle also designated for assignment left-hander Nick Margevicius and outrighted right-hander Matt Koch to Tacoma after he cleared waivers.