Michigan -3
Michigan is 8-3 SU and 5-5-1 ATS at home this year which is not overwhelmingly convinving. But, Ohio St. is not a good road team at all with a 1-6 ATS record.
For the most part, over the last month, Michigan is playing up to expectations and beating the teams that are worse than them (Mary, Penn St, and Minn at home. Also beating NW twice) and losing to better teams (on road to Mich St. Iowa, Mary, Penn St. and at home to Purdue).
Ohio St. is just losing of late. 1-8 SU record. Losing at home and away to teams they should have beat (Neb, Minn).