Bill Belichick even commented that players from their practice squad are better than people on other team's rosters.
The Patriots essentially try to recruit tough, savvy veterans who are smart and can handle their coach. An interesting point was whether the people they were drafting/signing could "handle their coach", i.e. handle the way he coaches.
Thats very interesting as I read about lots of player/coach conflicts, which obviously hurt morale, team unity, player focus, etc. The Patriots put an emphasis on making sure that everything works smoothly so they can focus on working football games.
The so-called "80/20" rule, where coaches spend eighty percent of their time worry about twenty percent of their players, doesn't really apply to the Patriots because they put effort into making sure all the players can "handle" their coach and don't cause the problems that become distractions.