To follow this argument to its logical conclusion, the same is true for all the rookies and UDFA QB's in the league. Why bother drafting a QB in the top of the 1st. After all, we don't know. Maybe the 4th rounder is just as good.
It is my personal belief that any fan who believes that Stidham is a better prospect than Tua is delusional. And, yes, I well understand that we are free to believe that Stidham is a top QB, and that some of the UDFA WR's will be top contributors in 2010.
There is no way to prove that some with ZERO experience isn't an all-pro quality player. After all, some all-pros have indeed been drafted in the 6th round or were UDFA's. These facts do not make it reasonable to expect Stidham to be a top QB or even as good as ANY of the other AFC quarterbacks. I suspect that he is the 3rd-5th best QB of the five (including Fitzpatrick). Rosen isn't included because he has probably been ruined by now (if Rosen were on the patriots roster, that might be different).