Theo Epstein certainly deserves his fair share of criticism, particularly, I guess, for the financial hole he dug the team into in 2011. I'll always give him big credit for helping assemble two title teams though. I said help, because it was clearly a group achievement.
People say he left the team in a big mess. That's only partially true IMO. It took one blockbuster trade to clean up the mess and reset things. A lot of the current team and top prospects come from the Epstein era.