I am a firm believer that systems the coaches put in have the greatest effect on whether a team is a winning or losing team. It's all the system Belichick has put in place in NE. When they lose players to free agency or injury, other ones step right in to fill the role. Look at last year with Brady and his no name receivers and somehow they make it to the divisional round of the playoffs. I'm not saying that Brady isn't a great QB, but once Brady retires, expect Mallet or whoever to come in and still win. As long as Belichick is there, they are going to be good.