Ohio State has improved dramatically from where they were in their first three games when they only beat Minnesota by two TD's, lost to Oregon, and struggled with Tulsa.
The offense gets all the hype and deservedly so but the defense seems to be peaking at the right time. Purdue put up 31 points and a decent amount of yards but that may be misleading because the game was over almost before it started. While tOSU was amassing their 28 point lead the Boilermakers had one nice TD drive and three short drives culminating in two punts and a fumble.
Look, if Ohio State plays like they did in the first 20 minutes of the Purdue game and the first half of the MSU game then the Buckeyes will win easily. How well Michigan plays will simply determine how bad of a loss they take.
That said, Michigan's defense is much better than MSU's and Ohio State isn't nearly as bad of a match up nightmare for them as for MSU so I don’t expect the Buckeyes to replicate the MSU game.