I think I get what you're idea is here, but getting an owner to "buy" into that theory would probably be a tough sell and here why I think it won't sell:
Usually the QB is the best player on the field, at least that's what you hear all the time. How to you justify paying top dollar only to have the guy sit on the bench for the game or half of a game? Or do you take maybe to QB's who are on the average pay scale, like 2 ex pats qb's, Brian Hoyer and Matt Cassel splitting the duties. Cassel, as you know was more than serviceable going 11-5 when Brady went down and Hoyer, even though he just stunk the joint out, isn't all that bad, do you take 2 guys like that and fit them in your model? I doubt you can get a Manning/Brady tandem?
Anyway, that's what I think you're trying to say and I like the idea.