You simply cannot understate the impact of a coach like Brian Van Gorder on the entire team. His willful stupidity is a direct cause of defensive players just giving up and not putting forth any effort. The front 7 stops making any effort on a pass rush, because they know that the inevitable blitz that he has called will leave a hole with a 7-yard diameter that the Q.B. will find a wide-open receiver in well before they can get pressure. And the defensive backs don't bother to make much effort in coverage, because they know that his asinine coverage schemes will leave at least one receiver wide-open on a go route somewhere else on the field. This cascades into piss-poor tackling effort, as well. The snowball then rolls into special teams and overall team effort: Why fight each play when you have a defense that cannot make a stop and will give up an average of 7 touchdowns each game?
From a P.P.G./P.A.P.G. standpoint, they were +9, +5, +19, +10 in the last 4 years. After adding Van Gorder, they are -20.