Gruden loves Peterman and I think it's safe to say that Gruden knows more about QBs than any of the armchair coaches here.
https://247sports.com/nfl/pittsburgh-steelers/Bolt/Nate-Peterman-gets-the-nod-as-Jon-Grudens-Top-QB-in-NFL-Draft-52378356
I don't know if he will be a long-term starter or not, but it's stupid to write him off.