It's really 3 things for me
1. First and foremost: Lack of Greg Hardy leaves us with only 1 perennial pass rusher who is in turned shut out of the game with double teams. Horton and Ealy benefit from Johnson being targeted at times, but they aren't talented enough to draw attention themselves. Hardy opens the entire defense up to cause chaos.
2. Close second: The secondary is piss-poor pitiful. They all suck. Norman has shown signs, but he's too inconsistent to say he doesn't suck right now. They aren't very good. It's simple. Now, you can blame the players, their lack of execution, and blatta blah blah. But the fact that this is what the FO has given this coaching staff to work with, the players can't be blamed for being told to start and play. The FO is fully at blame for fielding these players.
3. Third and less important but still worth noting: By and Large, our linebackers are inconsistent in coverage. Great tacklers, great at locating the ball, but the weakness of Luke/TD/Klein is the fact that they collectively are below average in zone and man coverage
Basically, I blame this coaching staff for game management and situational adjustments on both sides of the ball. I do not, however, blame this coaching staff for the defense, the offensive line, or the lack of weaponry on offense.
Essentially, Dave Gettleman takes the majority of the blame for this. These are the players that HE chose to give the coaching staff to work with.
The lack of talent can't be put on the players or the coaches. The players aren't very good, they shouldn't be on this team as the best possible options. Simple as that. But, you can't blame the players for playing and you can't blame the coaches for choosing from what they've got.