Red Sox designate Sean O'Sullivan for assignment, recall Marco Hernandez

The Red Sox have designated Sean O'Sullivan for assignment, and will likely recall a position player in his place to finally put their bench up to full strength.

This one was always going to happen, no question. One of  Brian Bannister's projects, O'Sullivan has enjoyed surprising success in Triple-A, but it really hasn't carried over to the major leagues. He managed to hold on in his first outing, but was touched up early Sunday against the Astros, and couldn't escape the fifth.

The Red Sox, meanwhile, have no need for a fifth starter for a while thanks to their hectic schedule finally easing up in the weeks to come. They can get through the rotation twice before needing to find another man to pick up the ball, and even if that seems like it's going to include Clay Buchholz for now, it doesn't need to include Sean O'Sullivan, particularly since the Red Sox also seem determined to give the Joe Kelly experiment yet another chapter.

Until the time comes that they do need a fifth starter, the Sox will likely keep on rolling with their extended bullpen, and now finally add another bench player. Best bet: Marco Hernandez returns to give them a lefty to turn to.

[Update 5/16] The Red Sox have indeed called up a position player, and it's Marco Hernandez. The infielder is being slowly transformed into a utility player with some outfield exposure in the minors, and is batting .333/.386/.441 in 101 plate appearances with Triple-A Pawtucket.