Bill Belichick has always called the defense. The sports radio discussion in recent weeks has been whether he had passed the play calling to one of two defense assistants and had taken those duties back after their losing streak at the beginning of the season. They have now won six in a row.
I don't think that is true. Actively calling the defenses during the game is one thing, overriding or chiming in on defenses during the game is another thing, game planning is another, and building the defense is yet another.
In the case of the Patriots, there is no question that Belichick builds the defense, and oversees the game planning, both in conjunction with an existing Defensive Coordinator like Dean Pees or Matt Patricia. I have no doubt Belichick takes the lead and has the final say of the overall defensive game plan.
Heh, THAT is not even debatable!
In all my years of watching (I began watching the Patriots around 1993 after a time-out from football for about a decade because I was so obsessive about it...I had a half a season ticket for a few years...:) the active calling of defenses was done by the Defensive Coordinator, and sometimes, they would put it on a subordinate such as the Linebacker Coach I suspect to ensure that if the Defensive Coordinator dropped dead, someone else could step in without having to do it cold.
However, I do admit I don't know about this year, as they don't have a real Defensive Coordinator and it may be true that Belichick has been doing it the whole time this year, hence the conversation I heard discussing it.