I think I could make a case for 9 time Pro Bowler Warren Moon on my list too by the way. When you factor in his CFL and NFL years, he had more passing yards than anybody else when he retired. In fact, he still is second on that list, with an almost 5,000 yard lead over third place Brett Favre.
I know yardage doesn't equal wins or championships, but it is a testament to how well he did the important part of his job - anybody can hand a ball off to an RB, but not anybody can make pass completions, especially for that many yards.