Andrew Bailey was supposed to be the team's closer, and he was injured just before Opening Day.
Carl Crawford was also expected to join the team shortly after the season began. But he experienced a setback in his recovery from offseason surgery and hasn't played an inning yet for the Sox in 2012.
In-season, the team hasn't had much better luck. Jacoby Ellsbury separated his shoulder in a fluke play against the Tampa Bay Rays in the team's home opener. The team has certainly missed his impact at the top of the lineup, on the basepaths and in the outfield.
Of all of the injured Red Sox players, Kevin Youkilis is the one most likely to return soonest. The team's starting third baseman has been out for a while now with back stiffness, with Will Middlebrooks filling in quite capably during his absence.
While the team certainly isn't making any excuses for their struggles, each of these injured parties will certainly give the Red Sox a boost if and when he makes his way back. Who do you think the team is struggling most without?