Perhaps the oddsmaker is taking just the final score in Indiana's last three games into account because I find this total to be too high. The Hoosiers have played two overtime games during their last three matchups. If you go by regulation, the Hooisers are holding their last three foes to 62.3 points a game. 
Ohio State, like Indiana, gives up an average of 68 points per game. The Buckeyes have held four of their last six opponents to 67 points or fewer.