McNabb is in the top 10 quarterbacks in the league, year in and year out.
The Eagles front office is in the worst 10 year in and year out.
A quarterback can't win without at least one good wide receiver and at least a mediocre offensive line. (Unless your last name is Roethlisburger and you have 2 very good wide receivers to throw to) Even the great John Elway took over a decade to get his first ring because of mismanagement.
When the Eagles had TO (say what you will about him you cannot deny his skills) they won the NFC championship, since TO left their best receiver has been Brian Westbrook a runningback. McNabb has had absolutely no one to throw the ball to, and until he gets another good receiver the Eagles can throw as much money at McNabb as they want, they will not win.