Okay, this is what I've heard.
The delay in hiring Davis was in determining his exact role, as he wants to be a head coach again and Schiano wants continuity during his tenure. Davis will be assisting the DC in any manner needed and helping blend the DC's vision with his/Schiano's. He's giving Schiano a lot of flexibility in his DC hire in that he can pick whoever he feels most comfortable with and not worry about experience since Davis will be able to provide plenty of that.
Safe to say after a good year or two, Davis will be looking for a HC gig. Interesting scoop. Thanks