I hope there is significant drop off after the starter IF you don't have a really good backup. BUT there should also be some teams that don't have a good QB in the first place.
Any QB with a passer rating lower then 80 should be significantly worse the then one with a ratings over 95. This is assuming they threw over 150 passes so you really know they have some time in the game.
Looks at the stats:
http://www.nfl.com/stats/categorysta...2&d-447263-n=1
Seneca Wallace had a better year last year then a lot of starters and should be rated such. Statistically he was playing just as well as Cutler or McNabb for the time he was in the game, he had about 40% of the attempts. Eli Manning and Schuan Hill also performed about the same level with passer ratings around 87.
Compare that to players like Russell 77, Bulger 71, and Orton 80.
There was only one player over 100.
four between 95-99.9 or over,
four between 90-94.9,
eight between 85-89.9,
seven between 80-84.9,
seven below 80
Now of course there are more things to looks at then just that such as: Post season play, yards, wins, fumbles, and rushing stats.
BUT there are a lot of starters no better then some teams backup or even worse. And a lot of this years rookies I think are over rated.