The defense has been fantastic, I think the yards are down partly because of some of the blowouts the Bills have lost and won, the fourth quarters have sometimes been both teams trying to just get the game over. But the points being higher is partly due to the turnovers by the Bills offense, not just the pick sixes, also the short fields and three and outs. Also, this defense totally changed after the first half of week two when McDermott took things over and showed Frasier how its done. All in all, I am not sure I consider these guys the best defense in the league but based on yards given up they are. They are definitely one of the better defenses in the league.