Only 1 of the 4 (Ohio State) played Iowa - 5th place
Only 1 of the 4 (Penn State) played Minnesota - 6th place
Only 2 of the 4 played Illinois - 7th place
Only 2 of the 4 played Wisconsin - 8th place

So, among the top 8 teams, there are only 9 games total that matchup those 8 teams

On the other end of the spectrum:

They all four played Purdue - last in the conference.
3 of the 4 played Maryland - 2nd to last
Only 1 (Penn State) played USC - 3rd to last
2 of the 4 played Northwestern - 4th to last
3 of the 4 played Michigan State - 5th to last