Interesting point, there. Under the offensive genius that was Chan Gailey last year, the Bills achieved:
Total Yds/G - 342.9 (19th)
Rush Yds/G - 138.6 (6th)
Pass Yds/G - 204.3 (25th)
Points/G - 21.5 (21st)
So far this year, under the rookie OC Hackett with the rookie QB(s), the Bills have achieved:
Total Yds/G - 344.2 (16th)
Rush Yds/G - 148.8 (3rd)
Pass Yds/G - 195.3 (28th)
Points/G - 22.7 (17th)
Which is, to be honest, not terribly different. Overall yards per game about the same, slightly more rushing yards per game, slightly fewer passing yards per game. Plus better points per game. (Smaller sample size, I know.)