I've heard this before, and it really bothers me. They needed him EVERY game. The only games where he pitched poorly were games that the Red Sox were well ahead of the playoff race.
The 2011 Red Sox got to an awful start, and were far below .500? Jon Lester had a 2.52 ERA in April.
When the team was pulling its self together, he struggled a bit, but managed to pull a 4-1 record in May
And what about when the team needed to pick up ground on its AL East foes? 2.31, 1.56, 2.78 ERAs in June, July, August.
And what about the very last game of his season when a must-win game against Baltimore? 6 innings, 2 runs. Can you really complain about that?