Whether or not it's working is irrelevant (although it seems to be now). Buying championships isn't easy, just ask Snyder and Steinbrenner.
The Bruce Smith/Deion Sanders years were when Snyder was running the team. He has now handed control to Gibbs and is doing exactly what Gibbs wants him to do as far as personnel. While you are right in that the skins aren't adding top-flite football players, they are adding the best free agent players available at the position, and paying them like even better players than they are. That's exactly what the Yankees do. They pay a little more than any other team would be willing to, even for only the guys who are the best available.
Would you give a guy like Adam Archuleta a 6yr 30 million dollar deal? That's the same deal that Roy Williams got, and they are hardly the same player. They gave Randle El 7 years and 31 mil. Burress, a #1 WR, not a #3 like Randle El, got 6 and 25.