Maybe it's unfair to judge Schilling on one outing, and we should remember that he gave up big hits to two pretty good hitters, Sheffield and A-Rod.
Nonetheless, the Schilling to the bullpen move has not made sense to me since the Sox announced it. I think that there's a lot that Schilling and the Red Sox aren't telling us. I don't think they're expecting Schilling to be able to start for the rest of the season. If he was making progress in his rehab starts, they would have continued with it until Schilling was ready, even if it was September. To do well in the playoffs, the Sox need Schilling to be an effective starter.
However, they chose to move him to the bullpen. Schilling will not be rehabbing his foot and building his endurance while sitting in the bullpen and throwing a few pitches every other day. Schilling isn't continuing his rehab now, he's pausing it. During his bullpen stint, Schilling may be able to improve his foot through some exercise, but he won't be getting his body ready to start.
When the Red Sox decide it's time for Schilling to start, it may take weeks for him to work his way up to pitching seven good innings.
It just doesn't make sense to delay Schilling's work to become a starter again. This is why I think the Red Sox don't think Schilling will be able to start this year. Knowing Schilling probably won't start this year, the Red Sox decided to take a chance and try Schilling in their struggling bullpen.
I hope I'm wrong about this one.