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06/23/09 8:53 PM ET

Kelley enjoys productive bullpen session

Mariners reliever working way back from strained oblique

SEATTLE -- Injured Mariners reliever Shawn Kelley was in good spirits on Tuesday after throwing 33 pitches -- mixing in his entire repertoire -- in a simulated game at Safeco Field.

Mariners manager Don Wakamatsu said Kelley will throw another bullpen session Thursday, then make two appearances in Arizona for the Mariners' extended spring training team before rejoining Triple-A Tacoma for two or three outings. Wakamatsu added that the team plans to activate Kelley during the next homestand.

So far, so good for the 25-year-old right-hander.

"It was amazing," Kelley said of the simulated game. "Just to be out there and throwing to hitters and getting some feedback from the hitters, just as far as them swinging at pitches and stuff."

Kelley was originally placed on the 15-day disabled list on May 6 with a strained left oblique, the most time he's missed due to injury since undergoing Tommy John surgery in 2003. He's 1-1 this season with a 1.54 ERA in 10 appearances.

"Today was a big step because you get the hitters in there, you step it up another level, you test it out a little more," Kelley said. "Today was a huge day for me, and it couldn't have went better."

Wakamatsu can't wait to have him back. Kelley would add another hard-throwing arm to a Mariners bullpen that has thrown a lot of innings lately.

"He gives us tremendous depth and versatility," Wakamatsu said. "Before he left, his velocity was up to 95-96, and you could see this guy in the seventh, eighth or ninth. He just adds another valuable piece to that bullpen down there."

Christian Caple is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.