You are not grading the performance of Drew Brees. You are grading the performance of the New Orleans Saints team quarterbacked by Drew Brees.
Again, how do you know this? You still haven't answered the question, by the way - because you don't know what method I'm using to evaluate Drew Brees. You have no idea! I pointed out stats that reinforce my case (yes, stats can be used to judge a QBs performance - they are a direct measurement of his performance on the field), but that's it.
And you DO realize its all subjective, right? That's why there are some teams who will likely trade the rest of their drafts in 2010's to move up for Andrew Luck, and other teams who wouldn't give up more than this year's first for him.
Unless you focus on the QB specifically with the intent of isolating his performance from that of his team, you might just as well be watching Jersey Shore.
You would have to make hundreds of adjustments to do it intelligently. Let's just talk about the completion percentage stat you called your accuracy stat.
Hundreds? Seems to me you're the one not doing it intelligently. There is a 'common sense' aspect to judging QBs, Oldfan. If it looks like a duck, quacks like a duck, its probably a Rex Grossman pass. For instance, common sense dictates that it is impossible for Rex Grossman to throw for 5400 yards at a 71% completion rate in 16 games. Common sense dictates that it is a very hard thing to do, seeing as how only one person in the history of the NFL has ever done
either thing, let alone both in the same season.
What's ironic is, your method seems to be the most simple of all - and probably the most incorrect. "You just isolate the QB!" One, that is impossible. 2, to accurately isolate the QB would take a lot of statistical regressions and analysis, not just you saying "I think Jay Cutler is the best." You're talking out of both sides of your mouth.
You could take the very same QB and manufacture a high completion rate in any number
of ways. Tom Brady has a much higher completion rate throwing from the shotgun than he does from under center, most QBs do. So, to analyze this stat, you might begin with the percentage of passes thrown from the shotgun. Peyton had the highest in 2010, at 75%. So, how can you fairly compare his completion percentage to a QB who throws only 30% from the gun?
Easy, you would say QB2 is not as good as Peyton. Actually, any QB who is only 30% from the gun would not be in the NFL.