Essentially I'm going to agree with Dipre, the fangraph you use is allowing our strong positions to carry our lesser positions. However when you look at the most important defenders, (up the middle defense) the # of games started by Julio Lugo and Nick Green are a tremendous discomfort to the overall defense, as well as Ellsbury's very much lack of defensive skill at the moment. Our catchers suck hard in terms of throwing runners out, as the Angels ran on us all day long.
In reality the team as currently constructed is less about the 3R HR, and moreso about winning that 3-2 or 3-1 game with strong pitching, and depth there, as well as a very strong defense.
With the additions of Beltre, Scutaro and Cameron and the shift of Ellsbury to LF, where in limited action has an excellent UZR rating..leaves us with only catcher as a weakness in terms of defense.
Enjoy the season, you're going to get old school Boston baseball, being blue collar and grinded out.