From each conference playing a 13th game in the CCG. That gives you 12 potential teams plus ND vying for 12 spots. Assuming the MWC drifts into the woodwork. Making a 12 games 1 loss team look better than wait 13 game 1-2 loss team is going to be hard. Especially since in most cases all 13th games will be between top ranked team
The odds are no in our favor