I have to hop on the bolded because part of my personal agenda is exorcising from this board the misguided opinion that "players win games."
The two most important factors in the success of an NFL football team is:
1) Coaching
2) Quarterbacking
You need both to be successful.
As to the rest of the team, most teams are very similar in talent and more to the point, a team with better coaching and quarterbacking will destroy a team with (for instance) better offensive and defensive lines.
It's hard to express how bad a coach Dave Wannstedt was.
And yes, he cost us more games than any non-QB player ever could have.