The problem is that rings are a team effort. When it comes down to it it's really hard to determine how much a great QB does that is from his effort, and how much is due to a solid O-line and receivers with good hands. Brady is a superb QB, so is McNabb, but Vinatieri deserves as much credit for Brady having the rings as Brady does. And Bruschi. And someone from their line (it's sad when the most important part of a team are largely anonymous).
Exactly. A championship QB may have weaknesses that just aren't apparent. It's what makes it difficult to criticize objectively. Brady is a very efficient QB. Could he do the same for another team? We won't know until he does.