USC plays primetime all the time on ABC. If they aren't primetime, they are the late afternoon game on ABC. I'm not buying into your theory.
The 3:30 ABC games are always split regionally, and the eastern half of the country almost never gets a Pac 10 game. (Remember USC and Oregon last year? One of the most anticipated games of the year, and nobody east of Denver saw it.) I need to write myself a note to check at the end of the year, as this is a pretty interesting question, but I bet that four or fewer of USC's games this year are widely available on the eastern half of the country. This is a relatively rare opportunity for USC to have the stage to themselves to impress the voters.
The 3:30 ABC games are always split regionally, and the eastern half of the country almost never gets a Pac 10 game. (Remember USC and Oregon last year? One of the most anticipated games of the year, and nobody east of Denver saw it.) I need to write myself a note to check at the end of the year, as this is a pretty interesting question, but I bet that four or fewer of USC's games this year are widely available on the eastern half of the country. This is a relatively rare opportunity for USC to have the stage to themselves to impress the voters.