He did it without issue last year, he was outstanding, so I'm not buying that as a problem.
We have a 5 deep rotation, a clear ace without a clear number two, any one of the other 4 can go two times through the order.
Playoffs are so much about your bullpen now, I think some people here still think it's 10 years ago. There's not much to choose between the other four starters, so take the one that could be a lethal weapon in the bullpen and put him there.
I think people are underestimating the impact he might have out of the pen. Consider adding an Andrew Miller type lefty to this bullpen, we don't have that and he has similar ability, I'm not even exaggerating. Both his walk and home run rate (lately) have been excellent, and I think he can easily give you 13-15 K's per 9 out of the pen. That's game changing. It's potentially series changing, with almost no cost to your rotation.