AP

Seattle Mariners pitcher Eric O'Flaherty reacts after giving up a solo home run to Baltimore Orioles Aubrey Huff in the eighth inning Monday, April 7, 2008 in Baltimore. The Orioles won 5-4.

SEATTLE - Pitchers Arthur Rhodes and R.A. Dickey were brought up Monday by the Seattle Mariners, who optioned struggling reliever Eric O'Flaherty to Double-A West Tenn.

Seattle also placed outfielder Mike Morse on the 15-day disabled list after he dislocated his left shoulder diving for a fly ball on Sunday.

"With the injuries we've had our pitching is a little beat up," Mariners manager John McLaren said. "Going to 12 pitchers will allow us some more protection while we battle through this stretch. Both Arthur and R.A. were very good this spring, and have thrown the ball well in the minors."

Rhodes, a non-roster invitee to spring training, had elbow surgery last May. He pitched well in spring training and stayed behind in Arizona at extended spring training to do additional rehab work.

In his one outing with West Tenn, Rhodes allowed three runs -- one earned -- and recorded just one out.

Dickey may be used in long relief or eventually as a starter. The knuckleballer has made two starts with Triple-A Tacoma, going 1-1 with a 2.40 ERA. In his last outing, Dickey carried a no-hit bid into the seventh.

O'Flaherty was expected to take over the main left-handed relief role after George Sherrill was part of the trade that brought Erik Bedard to the Mariners. But O'Flaherty has struggled, allowing runs in six of his seven appearances. On Sunday, O'Flaherty gave up six runs and eight hits against the Angels, watching his ERA balloon to 20.25.

"We think giving Eric some time to straighten himself out will benefit him, and us, this season," McLaren said.

Morse had an MRI exam on Monday that revealed the dislocation. He had played in just five games in the regular season, but hit .492 in spring training to earn a roster spot.