The way the schedule and the rotation is currently set up - John Smoltz will pitch against the Tigers at Fenway on the 11th and then against the Rangers on the road on the 16th. He needs at least one quality start in one of those games or he's done in Boston.
There is no way the Red Sox can afford to start him the 22nd against the Yankees if he hasn't pitched at least one quality start. No way.
Keep an eye on Michael Bowden in Pawtucket. The Red Sox may alter his schedule to be able to step in and take Smoltz' rotation spot.