Jon Lester is a legitimate ace, and Josh Beckett had a nice bounce-back year in 2011; but behind them it gets a bit dicey. Third starter Clay Bucholz has shown the ability to be a front-line starter but is returning from a stress fracture in his back that sidelined him for the majority of last season. If Bucholz can return to his 2010 form, it would greatly improve the rotation's outlook.
Behind Bucholz in the rotation is last year's set-up man, Daniel Bard. No one will argue that Bard has dominant stuff, but it remains to be seen how he will handle the transition from a reliever to a starting pitcher. As the season progresses, the Red Sox will have to monitor Bard closely, since his previous career-high in innings pitched is only 74.2 for a season.
Currently manning the fifth spot in the rotation is Alfredo Aceves, who, like Bard, will be switching over from the bullpen. While Aceves does have some starting experience, he spot-started four games for the Red Sox last year, it will be interesting to see how he handles the responsibilities of taking the mound every fifth day.