Theo Epstein has taken plenty of grief for the management moves that haven't worked out. Even with a pair of World Series championships, Boston might still be considered a "glass half empty" town. Maybe we haven't booed Santa Claus, but while I'm waiting patiently, I won't say that it couldn't happen.
Here's the top ten OPS in the AL among qualifiers. You'll notice that the Red Sox have FIVE of the leaders, while no other team has more than two. You'll also recognize that three (Youkilis, Ellsbury, and Pedroia) all came through the Red Sox developmental system.
Player evaluation, just as everything else in Boston, is an inexact discipline. The Red Sox have been pioneers in using all the resources available to them (process) to optimize their performance. I'm sure that the general manager has had his share of 'agita' over the results at times, but he does deserve a lot of credit, even as a "big market" GM.