In my opinion, the apex was SB-39, and the decline began immediately thereafter. The Eagles mishandled TO, McNabb sustained his umpteenth major injury, and the draft became amateurish after Modrak was ousted.
Based on Reid's early success from 2000 through 2004, the organization gave him all the credit and all the power. During the 8 seasons between 2005 through 2012, the Eagles only had 1 successful season, and they snuck into the playoffs that particular year as the #6 seed with a pedestrian 9-6-1 regular season.
During that 8 year period, we watched the Eagles anoint Kolb a starter after 3 dreadful training camps (brilliant talent evaluation). After a few plays and a concussion, enter coach-killer Vick. After Johnson's death, the Eagles demonstrated that they consider coordinators to be the same as assistant coaches, and skipped the process, in order to revamp their lines around Washburn and Mudd. Since the games are won or lost on the lines, we saw how that worked out.