Return to their level of play in the decade of 2000s then they won't be left out any year.

From 1999 to 2014, just looking at the four conferences that the big 12 competes with for a spot in the playoff (i.e. Pac b10 acc sec) the ONLY year in which the four champions of those four conferences all finished the regular season including championship game with 1 loss or less was last year.

Every other year saw art least one champion with 2 losses or more.

4 years there were only 3 that did it.
6 years only 2 of the four champions did it.
And
4 years ONLY ONE of the four conferences had a champion with one loss or less going into bowl season.

This info coupled with the fact that the big 12 won't receive more money for hosting a championship game means they have good advisors that are telling them to play the odds.