Army/Navy on a day all by themselves...the absolute only college game that day...and on CBS...
Perhaps their AF game?
What else is regularly broadcast? A game against ND?
Easy to be high average when your denominator is low and at least one game is the absolute only game on for hungry CFB fans.
Navy has a similar component but they almost always play ND in addition to Army/AF and then hit other ones when they are competitive and playing other top conf teams...
BYU is compromised by late games amd a very large denominator with every single game broadcast somewhere...even our stinker games...