Here's a great passage on how much Bill Belichick values communication via "Gridiron Genius" by Michael Lombardi:
Once in New England, Belichick ripped all the numbers off the preseason practice jerseys. Everyone thought it was intended to confuse the media and other onlookers, but really it was to force the Patriots defenders to learn one another’s names and get used to talking during the play. Belichick always said that if you want to know how well a defense is working, just listen. Defenses succeed only if the players know the scheme. But they really thrive when the players are talking to one another on the field.