 The 2005 season marks only the eighth time in 50 years that exactly two teams have gone into the bowl season undefeated . This has been a major criticism of the BCS format , which does not use a playoff to determine the national championship . Unless there are exactly two unbeaten teams , both from BCS conferences , the choice of the top two teams can generate controversy . If more than two undefeated teams remain , then one or more of those teams must be left out . If one or fewer undefeated teams remain , then an opponent must be chosen from among the one @-@ loss teams , meaning that other one @-@ loss teams will be left out . 
