Schwartz drafted Stafford, and most of the guys on offense were either drafted or signed by him, and that's the only coach the offense has known.
Caldwell is supposed to be some genius with QBs, as is Lombardi.
I can't imagine it's easy to tear down someone's muscle memory in a season and rebuild what you want. I have zero experience to stand on that statement, it just seems logical to me.
For years we've heard about Matt's terrible footwork, terrible arm angles, Matt's decision making skills, etc.. I wouldn't imagine they can change all that in one season and have the second coming of Peyton Manning in the end.
I'm willing to give Lombardi another year with the offense and see if that rocket takes off. I don't expect this offense to make even a deep run this year, and we will see a lot of new faces on defense next year, so I don't expect the draft will help much either.
But another year of working could show real improvement... or I could be way wrong.