A's acquire right-hander Rosario from Boston
The AL West champion A's cleared room on the 40-man roster by designating outfielder Jermaine Mitchell for assignment.
Boston claimed Rosario off waivers from Miami on Oct. 17 after he spent the year in the Marlins organization. He began the season with a 1.04 ERA in 25 outings at Triple-A New Orleans while converting all 16 of his save opportunities. The 27-year-old right-hander joined the Marlins on June 8, posting an 18.00 ERA in four relief appearances before going on the disabled list June 16 with a strained right quadriceps. He wasn't back in the majors after that.
Copyright 2012 by The Associated Press
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