I don't think Pickett is an average QB, I'd say his ceiling is an average back-up. His career QB rating is in the 70's, yeah the scheme doesn't help, I agree, but I've seen him miss so many wide open guys, not just make a bad throw, but not even see them, then I've seen him miss throw to so many open guys, and his pocket awareness is horrible, rarely steps up in the pocket, always tries that spin move to the outside. A decent QB wouldn't miss throw on so many open guys.
The scheme in Cleveland wasn't helping Deshaun or DLT or whatever his name was, but Flacco comes in and the offense looks 10x better.