Some Football Outsiders D stats from 2007

[cstjohn17]

At this point, the theory you describe here has become essentially universal in the NFL. "Keep everything in front of you" and "prevent the big play" have become homilies for repeating to the media. As the NFL has become more and more of a passing league, with teams using more receivers more often and spreading the field horizontally, this is what defenses have had to do to adjust.

You raise some good points, please don't forget some other cliches "Play to win", "Play 60 minutes" and "We believe in each other".