Couldn't he continue to get stretched out in extended? Like others have mentioned I'd rather have him as a starter on Sep 20 than a reliever on Sep 5th. I think you have to evaluate how he does though. If he doesn't look like he will be able to take the workload as a starter just have him have a few appearances out of the pen.
We really don't even know how effective he could be. Who's to say he is the same pitcher as last year.