Great question. I would say offense because there is more talent on the offensive side of the ball and part of the defense's problem is that they are always on the field. Even if the defense was playing lights out we have scored 13, 10, 14, and 7 points in our losses. That might be enough to beat the Browns, Jags, and Chiefs, no where near enough points to compete in NFL 2012.
What's worse: Titans offense or defense?