Really, I would say the two most important factors when setting up divisions would be to maintain the biggest yearly rivalries for revenue generation purposes and minimize travel costs. To cover the first part in the Big Ten, you keep IU-PU together, and you keep OSU-UM-MSU together (and, to a lesser extent, UI-NW). To cover the second part, you keep PSU with the teams close by, and the divisions work themselves out. An "eastern" division of IU-PU-PSU-OSU-UM-MSU, and a "Central/Western" division of NW-UI-IA-UW-NU-MN.