It does make sense that people are less willing to go out in the cold for 4+ hours when the game is less meaningful or even meaningless (when the team is hopeless or when the team has clinched). I can't say why people wouldn't buy tickets when the games actually mean something, and they very well may this year. I'll bet that 2 of those 3 games sell out quickly if the Bills get to 7-3; I don't have a lot of hope for the Christmas Eve game.
Personally, I've been to the stadium in the cold a couple of times. It's miserable. Maybe that makes some think I'm not a "real fan" or whatever. I'd rather spend my sports dollars downtown because I like hockey much better than I like football, but even the Winter Classic was too much time in the cold.
For those jumping on PTR's case, remember that the guy lives in New Hampshire and still has season tickets. I think he's pretty much beyond reproach on this one.