Matt Stafford is better than Alex Smith, but it's not, IMO, as good as even a guy like Matt Schaub. He's (right now) a third-tier QB after the elite tier (Rodgers, Brees, Roethlisberger, Brady, Rivers) and the very good tier (Flacco, E. Manning, J. Freeman, Sanchez, Schaub, Vick).
Stafford is on the next tier with guys like Sam Bradford, Jason Campbell, Cam Newton, Andy Dalton, etc. The transitional guys whose good games you can still remember, but are probably on the way up or on the way down.
Kevin Kolb is playing ball with Chad Henne and Kyle Orton right now. Good company.
But we're burying the lede. We're four weeks away from Terrelle Pryor starting an NFL game, everyone! Tim Tebow and Terrelle Pryor will be starting in the same division! Unfortinately, Denver and Oakland meet in their last matchup on the season November 11, so unless Kyle Boller is so bad that he gets replaced in four weeks, we're not going to see them on the same field.
Sam Bradford is nowhere near the level of Matthew Stafford.. Saying they are in the same tier is almost laughable.