Personally, I wouldn't put a number on this, because it really depends on who is available. And, as should be obvious to everyone, there ain't much available at the moment. (Hence, a discussion on the wisdom of acquiring Nick Foles.) I think the mistake is to scrap a team's current middling QB in search of a diamond in the rough. I don't fault anyone for the EJ pick-- it was a relatively low-risk pick, as first round picks go. We traded down for him, and he certainly, at the time, seemed to have potential to become something special. And, the idea of holding on to Fitz was a non-starter. But, it was the lack of Fitz (or even Trent Edwards, for that matter) that made the EJ pick so risky. Coming out of the draft without an established starting QB, even with one of those rare, superstar draft picks, like Andrew Luck (or RGIII!!!, remember his prognosis?) is shaky ground, indeed.
We should keep Taylor, and stop looking for other, equally mediocre QBs to replace him. Draft a QB high, keep developing Cardale, and move forward.