One reason for this could be that Gailey likes to run Spiller out of the 5 wide set because defenses swap out a LB for a DB in that case and Spiller has a lot more room (one of the reasons for his high YPC). Wade left the LB in and put man coverage on everyone and forcing the Bills to beat them in the air.. Basically Wade called Gaileys bluff. Gailey figured he could not run Spiller effectively with the LB still in, so he went pass happy.
Game, set, match, Wade.
The big picture question is, do other defenses start doing this the rest of the season as well.