Right, the only important defensive stat is points allowed. The Bills were right in the middle as the 15th worst in points allowed with 374 pts , an average of 23.4 pts per game. Yes, the offense was responsible for 35 of those pts with 5 turnovers resulting in TDs (4 by INT, the other a fumble) but that would’ve only moved them up a couple of spots based on only points given up by the defense.
With how pathetic the offense was for most of the season, it was just as much responsible for the 6-10 record.