Red Sox call up Jonathan Diaz, designate Clayton Mortensen for assignment

The Red Sox have called up infielder Jonathan Diaz from Pawtucket, designating pitcher Clayton Mortensen for assignment in order to clear a 40-man spot for Diaz.

This is pretty clearly a move necessitated by the hamstring injury suffered by Stephen Drew in last night's game. Since the team expects him to only miss a day or two, they can't place him on the disabled list and call up Will Middlebrooks, who isn't able to return to the majors within 10 days of being optioned without the Sox placing someone on the DL.

Diaz, 28, is hitting just .242/.350/.341 in 182 at bats for Pawtucket this year, and acts mainly as a warm body who can play third base well enough and maybe make the opposing pitcher throw a few pitches. This will be his first opportunity to play in the majors.

Clayton Mortensen had managed to avoid the dreaded DFA thanks to a series of injuries in the bullpen. Now, though, with the Sox needing an extra man on the bench to compensate for Drew, the team finally had to bite the bullet and drop him from the 40-man. Given his 5.34 ERA, he could potentially clear waivers, though some teams might look past his peripherals and take a flier based on his effectiveness in 2012.

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