This is far from a fully formed thought, but it seems like with Montgomery essentially piggybacking with Darvish for now, Chatwood is by default the long man, and needs to be saved for those situations where the starter doesn't go deep. With the way Lester, Hendricks, Q, even Hamels (besides last night) have been pitching, there hasn't been a lot of need for him. It's possible Chatwood isn't ready for/used to things like pitching back to back, as he's never had to do that in his career, so if you bring him in for an inning, he might be unavailable the next day, and trying to piece together 6 or 7 innings without Chatwood and Monty is pretty daunting right now. If he continues to pitch like this, he'll get more opportunities. And I think if Darvish shows he can pitch into at least the 5th or 6th consistently, that will free up Monty and give Joe more flexibility to use both of them.