If you're trolling to start an honest conversation about whether or not the defense or its individual players execute (i.e. play) well, sure I see your point and what you're doing.
If you're being serious and suggesting that Barry is a good DC and the players have let him down all season...no, I don't see that.
I think there have been almost as many times that the players haven't executed as there have been failings of the DC. The question of "bad DC or bad players" is BOTH.
Getting a good DC eliminates one problem and if you're lucky at least helps to coach up or elevate the ok players to good and the bad players to ok.
It's not hard to come up with criticisms of Barry's scheme and calls, I'll put it that way.
His defense put enough of a scare in MLF that he put his starters back in vs. DAL. Not a ringing endorsement.