Boise State had one difficult team on their schedule all year. Fortunately for them, they won.
TCU had roughly 2 tough games all year.
The BCS commish doesn't want to say it, but BSU and TCU play patsies for most of the season. They aren't going against SEC/Big12/Big10/PAC10 teams every week. Its easier to get up for a big game when you only have 1-2 a season.