PEORIA, Ariz. -- Right-handed reliever Shawn Kelley was optioned to Triple-A Tacoma on Tuesday as the Mariners reduced their Major League roster to 27 players, with two more moves still needing to be made by 2 p.m. PT on Wednesday.

Kelley, 27, had a good spring, posting a 1.98 ERA with 15 hits allowed and one walk while striking out 11 in 13 2/3 innings over eight Cactus League appearances, but he gave up a two-run home run to Yoenis Cespedes in the seventh inning that proved costly in Seattle's 4-1 loss to the A's in the Tokyo Dome last Thursday.

Kelley seemed to be a prominent part of the bullpen this spring after returning from his second Tommy John surgery last year and posting 12 2/3 scoreless innings in 10 appearances as a September callup. But general manager Jack Zduriencik said tough decisions needed to be made, and Kelley had an option remaining and thus could be sent to Triple-A without having to clear waivers.

"There are just some things he needs to work on," Zduriencik said. "He's still a young guy, and his time in the big leagues has been off and on with a few injuries that had a few setbacks here. Shawn has a good arm and there are some things he did real well, but there are some things he needs to work on, and we felt the best thing right now is to go to Triple-A and let him work on some things he's been instructed to do."

The move leaves 13 pitchers in camp, with 12 expected to open the season on the 25-man roster. Kelley's departure seemingly clinches a roster spot for rookie Erasmo Ramirez in the bullpen. The club still has three lefty relievers -- veteran George Sherrill, Rule 5 Draft pick Lucas Luetge and Charlie Furbush -- so one of those three figures to be the final pitcher cut.

Right-handed relievers still on the team are Brandon League, Tom Wilhelmsen, Steve Delabar, Hisashi Iwakuma and Ramirez. Kelley thus was the odd man out.

"You have to make decisions," Zduriencik said. "No one finishes the season with 12 pitchers. I guarantee you we're going to go down and bring him up at some point in time if he stays healthy and continues to compete down there. It's just the way it is. Someone is going to have to go, and in this case, it's Shawn. But it's not an indication of anything except that he has an option left, and if he produces, he'll be back. It's up to him.

"Shawn is a good kid. He understands. Players understand how it goes. The door is wide open to come back if he produces."

Kelley has spent parts of the past three seasons with Seattle, posting an 8-5 record and 3.66 ERA in 73 appearances.