Once he started to get healthy, Morales suffered a left pec injury.
Of late, Morales has pitched well in his Minor League rehab assignment.
Though the Red Sox were stretching him out as a starter in the Minors, Morales will return in a relief capacity. There are currently no openings in the rotation.
Morales will join Andrew Miller and Craig Breslow to give the Sox three lefties in the 'pen.
Ian Browne is a reporter for MLB.com. Read his blog, Brownie Points, and follow him on Twitter @IanMBrowne. This story was not subject to the approval of Major League Baseball or its clubs.