I think it's premature to say that Samardzija will be a bust in the NFL. Last year was his first year getting real playing time; he's got a lot of work to do with respect to learning the position. It's impressive for him to have enjoyed the success he has already, and for him to have demonstrated a combination of size, instincts to make tough catches, and athleticism that most NFL WRs don't have. If his senior season shows a significant amount of polish on his game and achievement at learning the position, I think he's likely to be a successful NFL WR. If he makes few gains this year in his individual play, I think it's tempting to attribute some of his great success to Weis rather than to Samardzija himself.
With regard to Quinn, I think that line of criticism is out of place. While it's true that Weis is an excellent teacher of QBs and Quinn owes him for his tutelage, Quinn's success has not been simply the result of a spread offense or some other QB-friendly system like Urban Meyer (Alex Smith) or Jeff Tedford (Kyle Boller) have implemented. Rather, Weis has done an outstanding job teaching Quinn to make good decisions with the football. Quinn's already-present physical gifts were not doing him that much good before Weis got ahold of him, it's true. But those gifts, combined with the learned side of QBing, make Quinn an outstanding pro prospect. The success of most QBs comes as a result of good decisionmaking with the football, and ability to recognize the right thing to do against millions of different defenses. It's that ability that separates Peyton, Tom Brady, Carson Palmer, Matt Leinart, and Brady Quinn from Ryan Leaf, Cade McNown, Kyle Boller, Jay Cutler, and a bunch of other big, strong-armed guys that never did anything in the NFL. It doesn't hurt Quinn to have learned his QBing from Weis. Rather, that tutelage is a gift that will likely serve him well in the NFL. There are no sure things in NFL drafts. But Brady Quinn is well-prepared to succeed, and it will be a surprise if he doesn't.
Regarding the rest of the list: I think a strong case can be made that Joe Thomas is the best player in the country right now, and should be the #1 pick. I think Ted Ginn Jr. should absolutely be on that list. I think Posluszny, Bush, and Landry are a bit too high, and I agree complete that Charles Johnson, Jarrett, and Adrian Peterson jump into the top 7 of that list if they declare.