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01/08/11 1:47 PM EST

Rangers acquire reliever Kelly from A's

ARLINGTON -- The Rangers have acquired right-handed reliever Ryan Kelly from the Athletics in exchange for pitcher Guillermo Moscoso, the club announced on Saturday.

Moscoso was designated for assignment on Friday to make room for Adrian Beltre on the 40-man roster. Kelly, who is not on the 40-man roster, is a power-armed reliever with an excellent walk-to-strikeout ratio who has spent the past two seasons at Class A West Virginia of the South Atlantic League in the Pirates organization. The Pirates traded him to the Athletics last month.

Kelly, 23, started once and pitched in relief in 37 games at West Virginia, going 2-3 with a 4.20 ERA and four saves in 75 innings. He allowed 75 hits, walked 14 and struck out 75. In 184 Minor League innings, he has allowed 204 hits, walked 43 and struck out 171.

He was selected by the Pirates in the 26th round of the 2006 First-Year Player Draft out of Walters State Community College in Tennessee but has been slow in developing because of some minor injuries. He missed time in 2010 when his foot was fractured by a comebacker to the mound.

"We have a lot of history with this kid going back to junior college," said Josh Boyd, the Rangers' director of pro scouting. "We like his arm. He touches 95, 96 in relief and shows flashes of a power breaking ball. We like the strikes and feel there is some upside there."

Moscoso, one of two pitchers acquired from the Tigers on Dec. 8, 2008, for catcher Gerald Laird, has a 4.30 ERA over 11 relief appearances in his big league career the past two seasons. He spent last season at Triple-A Oklahoma City, going 7-7 with a 5.18 ERA over 23 games, including 22 starts.

T.R. Sullivan is a reporter for MLB.com. Read his blog, Postcards from Elysian Fields and follow him on Twitter @Sullivan_Ranger. This story was not subject to the approval of Major League Baseball or its clubs.