While it's never fun to be a pessimist, it's important to be realistic.
Hope springs eternal every year in baseball, with all 30 teams hoping to take advantage of consistent contributions from every member of the 25-man roster (and then some). But at season's end we always tend to look back at three or four players who failed to meet expectations.
In 2012 it was Jon Lester who had the worst year of his career (9-14 with a 4.82 ERA), as well as Jacoby Ellsbury, who after posting MVP numbers the season before, missed a good chunk of the season with a dislocated right shoulder.
Of course hindsight is 20-20, but let's look into our imaginary crystal ball and observe the five Boston Red Sox players who are most likely to disappoint in 2013.