ND-OSU was between 2 midwestern schools & many didn't think the game would be close.
IU-scUM Involved one of the worst CFB teams of all time becoming a dominant team in CFB within 2 years & had a Heisman Trophy winner lining up behind Center. The other team was from the South.
Take all of that in consideration and it's easy to see why this year's NCG had more viewers.