According to this article, Iowa has a 26% chance of going 12-0, tOSU has a 10% chance and MSU has a 4% chance. Obviously tOSU has a harder schedule going forward but it still seems like the %'s should e closer.
http://www.blackheartgoldpants.com/2015/10/19/9563495/2015-big-ten-win-projections-post-week-7
http://www.blackheartgoldpants.com/2015/10/19/9563495/2015-big-ten-win-projections-post-week-7