The problem isn't necessarily the starters, its all of the close games they've played, and how they're being used. Lester went 7 innings yesterday, and somehow we saw 4 relievers.
We also keep seeing Miller come in for 1-2 batters, walking a pile, and then being replaced-- He's had 4 appearances so far, and in those, he's gotten a total 4 outs. Ouch.