He just isn't productive enough to be considered top 10.
But, you are probably wondering why Eli's 4th quarter clutch prowess means a little bit more to me than Smith's...well, its mainly because unlike Eli, Smith doesn't really have anything to show for it. Eli has 2 SB rings to show for it. Yes, winning the SB is a team effort, but if Eli didn't come through in the clutch in both those years...the Giants don't go home with any rings.
Believe it or not, but contrary to some people's beliefs here at PSD...winning multiple SB MVPs and having one of the best playoff records among active Qbs DOES indeed matter when ranking Qbs.
For me, it matters enough to put him ahead of guys like Romo, Rivers, Shaub, and Vick...guys who might be a little better statistically, and a little more consistent during the regular season at times (not this past season though), but don't have anything close to the playoff accolades that Eli Manning has (some of that being due to his team, but also some of it being due to his clutch play in big games and big moments).
So basically, yeah...win the SB is a team accomplishment, but Eli Manning is a big part of this team and his clutch play is what got them over the top not once, but TWICE.