I believe that the problem with the d line is that they watch too many 1940's musicals, wishing they were Gene Kelly or Fred Astaire. All they do Is line up against the offense and start hugging the linemen across from them like Cyd Charisse (google it).
There is no urgency with the defense. Just sit back and hope the offense screws up. Well, good offenses don't do that. McDermott will never figure it out.