The Red Sox designated lefty Fabio Castro for assignment to create roster space for new acquisition Eric Patterson, according to the team. The Red Sox acquired Patterson from Oakland over the weekend after the A's designated the infielder for assignment.
The Red Sox have called Castro up twice this year, but manager Terry Francona has yet to bring the 25-year-old into a game. In 17 Triple A appearances, he has a 6.65 ERA with 7.5 K/9 and 4.6 BB/9. Castro last appeared in a major league game as a member of the 2007 Phillies.