Regarding Giolito, a full recovery isn't so much when he returns or even how effective he is, but whether there are any setbacks -- especially the first year back.
Therefore, Houck, Bello and Crawford are the three sure things for the starting rotation. Gio, Crochet, Buehler, Fulmer, and maybe Sandoval could provide serious depth or serious doubt.
As far as durability right now, there are even less questions about the elbow macaroni group than Fitts and Criswell.