You mentioned both Coyle and McAvoy ... McAvoy is not the only defensmen not playing as they should. And Coyle they keep trying to make him into something he is not. And with many of these other players it is like they are square pegs being forced into round holes.
It is obvious McAvoy's development has been stunted and Coyle's greatest effectiveness is not being properly used.
Just my opinion, but from what I have seen in this year's team play combined the disturbing trends in team play over past couple of years lead me to believe much of the problem lies in the SYSTEM and the usage of the players.