There were three big personnel mistakes in the Andy Reid era.
1} Jerimiah Trotter left for the Washington Redskins after the 2001 season. He came back in 2004. His presence after the 27 to 3 loss at Pittsburgh really made a difference in the run defense.
2} After Hugh Douglas got 12 sacks in 2002, he went on free agency to Jacksonville. Like Trotter, Hugh Douglas returned in 2004; he was good both against the run and pass.
I do not believe Jermiah Trotter would have made any difference in the 27 to 10 loss to Tampa bay in the 2002 Championship Game. The following year in the 14 to 3 loss to Carolina, without either man, was a different story. That loss had it roots in two regular season losses; 23 to 21 at Dallas and 30 to 27 overtime at home to the 49ers.
The Eagles had to win the final game of the season at Washington to get the home field advantage in the playoffs. The 31 to 7 win was easy but Philadelphia lost Brian Westbrook for the playoffs. Had they defeated either Dallas or San Francisco, the final game would have been meaningless. Both Douglas and Trotter might have improved the defense against both teams. They could have played reserves with an eye to the future with the Redskins; and had Brian Westbrook for the post season. His presence would have made a difference against the Panthers. Scoring only a field goal, the team really needed him.
3} Jeff Garcia leaning for Tampa Bay after 2006. Leaving him go was a real insult after he played four great games-at home with Carolina then on the road against the other three teams in the NFC East. The Philadelphia Eagles required A.J. Feeley. They remembered in 2002 Feeley quaterbacking in five consecutive victories. Not so this time. Feeley threw three interceptions in the 31 to 28 loss to New England and the 28 to 24 loss to Seattle. Jeff Garcia may have done better. These two losses ended the Eagles playoff chances in 2007.