It may not have to do with your playbook, but it does have to do with your offensive system, so, sorry, but if you don't think that consistency in your scheme has an effect on a QB, his accuracy and his decision making, then you don't know football.
It's not just about the QB, it is also different WR routes every year. Different timing in those routes. Different blocking schemes every year. Different hot calls every year. Different terminology. Different playcalling in different situations.
And it's not just changes like going from one WCO play caller to another. We are talking going from the WCO in year one, to Norv-West-Air in year two, to a horrible OC trying to combine the two in year three to Martz's Air Coreyall offshoot, in which he didn't even play in because a wire that was left in from his surgery Nolan rushed him back from SAWED through a bone in his shoulder,bbut, you know, everyone thought he was faking, in year four to Singeltary's ground and pound in year 5, in which they had to throw more than Martz had because they were always behind. Then HALFWAY through season six to the spread, his old college offense from 5 years ago and now finally, back to a run oriented WCO (which seems like a contradiction in terms).
Now that encompasses now 7 OCs and now 4 head coaches. Plus a year completely missed due to injury.
Show me ONE QB that has had success in this type of situation and under these circumstances. Not gonna happen.
Alex Smith is still around and rated a 75 because pretty much everyone on the planet except 49er fans, who should get it the most, get what this guy has been through and all have all seen the flashes of really Fing good play and think that if he can get some consistency and a good coach around him, he may still be a star. He has the tools. He just need to sharpen them.
People also still remember that Steve Young was well in his 7th and 8th years before he really became Steve Young on this very team.
Now I'm not saying that is going to happen, but you don't know until you get all the pieces in place.