Geno Smith has already shown he could play well against some pretty good defenses last year, including an elite defense in LSU. It helps to have a receiver like Stedman Bailey out there, but make no mistake... Geno Smith is making the reads and throws that you want to see with touch and accuracy.
The eye popping stats are just for show and it's difficult for the typical fan to get past it. Stats are causational.
It wouldn't matter if he was putting up 200 yards and 2 TD's a game, the kid is an absolute maverick in the pocket and in the face of pressure. He's operating Holgorsen's offense at a level exceeding Weeden because Geno is much less prone to turnovers than Weeden. He also doesn't have the tendency to throw high over the middle and leave his WR's out to dry like Weeden.
He throws with a level of anticipation that you don't see in many college quarterbacks. A lot of teams are going to like the intangibles that Geno Smith brings and for good reason.
E.J. Manuel is the very definition of the word "project", and I think he's a coachable kid. However, I don't think he's underrated.
I can watch any college football game at random and see a quarterback with better throwing mechanics. He's ok in college because he's big and athletic, with a lot of talent around him. He's a good all around athlete and a good leader.
His throwing mechanics aren't efficient, and difficult to watch sometimes. He doesn't get any trunk rotation involved in his throws and it's more of a push, similar to Kyle Boller when he came out of Cal. The coaches rarely let him throw in the middle of the field. Most of his passes are to stationary receivers and he doesn't demonstrate throwing with timing and anticipation consistently.
Lofts a lot of passes and doesn't look comfortable throwing into tight coverage because he gets no torque from his core and the ball comes out with no zip. He's not comfortable with seam throws, deep outs, or crossing patterns because he doesn't have the consistent trio of timing/accuracy/velocity to hit moving targets in stride.
I think Manuel is more of a pet project for a coach who's looking to develope a good athlete with an intriguing combination of size, athletic ability, and leadership qualities.