Bart Scott is right. It's the players...they are soft and entitled, thinking that a magical DC is going to come in and save them.
The last time we had a great defense was under Mike Zimmer 15 years ago. Since then, we've constantly rebuilt, gone from a 3-4 to 4-3, and had Brian Stewart, Wade Phillips, Paul Pasqualoni, Rob Ryan, Monte Kiffin, Rod Marinelli, and now Mike Nolan at DC. At some point, you would think ANY of those DCs would be a hit but nope. So fine, if they want to fire Nolan then go ahead but I have zero confidence that anyone else can come in and turn this into a great defense, just based on history. At the end of the day, you just have to realize that there is a disconnect between the HC/DC and the front office with the players they give them.
McClay and Stephen are good at drafting when it comes to finding guys who can play in the NFL vs. being a bust. But all of those defensive players only seem to be good enough to produce individually for their own stats and payday instead of being able to contribute to the defense as a whole. It's like a basketball team full of scorers who all need the ball in their hand because all they can do is score. However, they can't pass or play defense and therefore, are a bad basketball team because there is only 1 ball.