People can question Belichick's ethics all they want, but he knows what he's doing from a scheme standpoint.
I hate that cheating ******* but the simple fact is that his teams are down on their fundamentals and make very few mistakes. As compared to, say, Tomlin's teams which don't seem to know jack **** for fundamentals (except for Munch's OL) and make mistakes and blown assignments all day long. Belicheat also does something that is a foreign concept in Pittsburgh, that being the halftime adjustment.