The defense has looked overwhelmed at times year, a couple games being pretty bad. But I swear people just forget how a BB works: start out slow in the beginning of the year, with lots of experimentation, and over the year they just get better and better. I gave up worrying about the D in the first two thirds of the season, it's the last third they turn it on. If the defense is still bad after week 10, that's when I start to worry.
That said, this year has been interesting with the jettison of Collins midway through the season. That, plus the Sheard benching really seemed to get the D going.