The Red Sox designated Darnell McDonald for assignment, according to Amalie Benjamin of the Boston Globe (via Twitter). The Red Sox had to make room for returning center fielder Mike Cameron, who is returning from an abdominal injury.
Cameron and Jacoby Ellsbury both missed significant time early on, so McDonald has played more than expected. The 31-year-old has essentially been a regular this year. He has played all three outfield positions, hitting .263/.320/.400 in 105 plate appearances. Like Jeremy Hermida, McDonald has batted more times than Cameron and Ellsbury combined. It wouldn't be fair to judge McDonald's defensive ability on 226 innings, but UZR suggests he has been below average to this point.
McDonald could be claimed by another team, but the outfielder has enjoyed playing for the Red Sox so far. He told Peter Abraham of the Boston Globe that he wants to stay in the Red Sox organization, though he understands the business side of the game.