Good QB play comes (often) with continuity with coaches and other players. If a QB is good in this league it’s doubtful they’ll be back in the next year, probably a 3rd qb in the NFL somewhere. That will be a big reason I think that QB play won’t be very good on a consistent basis. (unless the NFL allocated players to teams as sort of a developmental approach, I know that was kicked around as an idea but not sure if it is actually happening?)