I'm a stathead, so I wanted to relay the "Win Probability Added" (WPA) stats from Advanced NFL Stats to everyone here. WPA is basically what it says, how many wins does a player add to his team. You can see the results from this year here: Advanced NFL Stats - Player Statistics by Position
The best QB this year is Matt Ryan, adding 4.49 wins to his team. This number will likely go up as more games are played. For instance, last year Tom Brady added 7.91 wins to his team, Brees 6.91.
This year, Matt Cassel has a WPA of -1.12 and Quinn a WPA of -0.43. This means our QBs have cost us 1.5 wins. That is an atrocious number.
If we have a quarterback in there that has a WPA of 3, that's a swing of 4.5 wins and thus we are sitting as a 6 or 7 win team (2 + 4.5 = 6.5...hence why I said 6 or 7). This is all theoretical, but I'm just trying to display the power a good QB can have on this team.
The best Linebacker in terms of WPA, Lawrence Timmons of the Steelers, has a WPA of 1.83. If we took Te'o and automatically assume he becomes the best linebacker in the league in terms of WPA (which is very very very unlikely), then we'd assume we'd have 2 more wins roughly. He would basically offset the 1.55 wins that our QBs have cost us. We're still a 4-8 team.
If Geno Smith turned into just Russell Wilson, who has a WPA of 1.91, then this team has added the negative 1.55 wins that Cassel and Quinn are responsible for and another 1.91 wins from a better quarterback. So 3.46 wins. That puts us at 5-7 or 6-6. If Geno Smith turned into something more, then we're sitting even prettier.
What am I trying to get at? It's evident from this that QB is the weakest position on the team, so bad that they've actually cost the team 1.55 wins. And by the way if you think Alex Smith is the answer, his WPA last year was 0.60 and this year 0.89. No thanks.