In a BCS conference teams have to prep every single week like the team they're playing has a legitimate chance to beat them because they usually do. They have to play their starters the entire game. The rigors of the schedule demand that they have depth.
Boise plays opponents that are so bad it can pretty much just show up and win. Most of its games are over with at the half.
I'm sorry that Boise isn't in a BCS conference but the fact is that it is isn't. It is much easier for Boise to go undefeated than it would be for any other BCS conference team. If Boise wants to get in to a NC game, get in a BCS conference. Otherwise, tough luck.
Now of course this is all under the BCS system. If Boise were to get a to a NC game via a playoff system, then they would obviously deserve to be there.