In a nutshell, Belichick wants opposing offenses to make the necessary reads and adjustments after the ball has been snapped, which he hopes will lead to more offensive mistakes and more big plays for his defense.
Of course, when opposing offenses can simply line up and run the ball down your throat as teams did to the Patriots last year, all of the complex, confusing aspects of the defense are rendered useless.
Part of Belichick's hermit-like penchant for hiding in his dark office lit only by the television screen is that he is searching for predictability. He studies coaches' tendencies as much as those of teams. What did a certain coach do in this situation the last 100 times he was faced with it? Belichick would likely know the answer to that question and because of that, odds are in his favor that when that situation arises on Sunday, he will make sure the appropriate defense is called.
While the unpredictability of his defense snowballs in its own success and wanes in its failure, it still demands a tremendous amount of study from his players, who must know the goal of the defense as a whole on a particular play rather than simply their own assignment. In fact, the players are given a written test each week to ensure their readiness from a preparation standpoint.
The complexity of the defense is what will make training camp so interesting this year with so many new faces expected to contribute. With rookies Ty Warren, Eugene Wilson and Dan Klecko, as well as veteran free agents Rosevelt Colvin and Rodney Harrison, the defense has a new look. The rookies will have it particularly tough, although they were initiated into the system during rookie orientation and the June mini-camp along with some extra meeting work mixed in.
"We had a week after mini-camp where we still had meetings and then we stayed to work on conditioning," Wilson said. "I feel like right now, I'm not second guessing myself like I was the first couple of days when I got here. Right now I feel like I could go out and play the coverages and make plays and do what I'm supposed to do."
But figuring what the Patriots defense is supposed to do from play to play and week to week is a challenge in itself. Wilson's real test will come when he begins preparing the first few weeks of the season and realizes how much study is needed.
Additionally, the club is allegedly switching to a full-time 3-4 base defense this year, which will end up being a bunch of talk for a team willing to play multiple fronts in one game, never mind from week to week.
"We do so many different things and play different kinds of coverages. So it's basically real mental here where in college it was more about athleticism. They would call one coverage and you would play that coverage. Now we have to see the checks, see what kind of drop-back the quarterback is taking, you have to worry about so many different things.
For his part, Belichick simply follows his teaching model, even with all the new faces. To his credit, he recognizes that not all players learn the same way.
"You teach them in a classroom, you teach them on film and you teach them out on the field," Belichick said. "Then you run it and correct it. Players will meet individually with the coaches to specifically go over different aspects of the defense, but otherwise it's just repetition. If a guy doesn't understand something, you try to find a way to explain it to them or show it to them either on previous years' film, on the practice field or on the blackboard. There are always going to a few bumps in the road."
But with several new defenders being counted upon for contributions, Belichick hopes he can pave the way for a smooth drive back to defensive prominence.