It seems, as with any good team, the people responsible for that get promoted and become head coaches other places. It has happened with Tony Dungy, it has happened with Mike Holmgren, and it is happening with BB. What it creates, however, is this over-demand for certain types of players. When Dungy was in Tampa Bay, he ran his Tampa-2. He could easily get the players to fit that scheme because they were not in demand elsewhere in the NFL, because nobody else was running that scheme. Then he moved to the Colts, implemented a Tampa-2 there. Now many teams run the Tampa-2. Look at BB's system. He was the first coach in a while to seriously run the 3-4 defense the way he ran it. RAC, Mangini, and now McDaniels will be looking for the same types of players that BB wants, creating a scarcity of them. When you come in with a new system and have success (partially because nobody really wants the players that fit your system) other people want the players that fit your system, and it becomes harder to run your system. I want all the good players to stay on the Patriots!