Ohio State actually had a three-score lead in the 4th quarter before Minnesota added some obligatory points in garbage time. So, I wouldn't say the Buckeyes struggled. Shoot, they were about to go up 21-0 in that game if a ball carrier had not fumbled on the 1 yard line.
If you say Ohio State struggled with Minnesota, I could say Bama struggled with an LSU team (who they should have lost to) that couldn't score against Arkansas, who had a 17-SEC losing streak.
Florida State's struggles are well documented.
You could argue that Mississippi State failed its first real test in losing to Bama. Prior to that, they struggled against lesser opponents.
And outside of TCU, Baylor and Kansas State, the rest of B12 is just as bad as the rest of the B1G after you get by Ohio State, Michigan State and Wisconsin.
The only school that really doesn't have a major demerit against them is Oregon. They've beaten Michigan State, UCLA and Utah as far as ranked school go. They lost at home to Arizona, but the Wildcats are a solid football team in a really good Pac-12 South.
If you closely examine the schedules of all the top teams, you'll find flaws. No team ranked in the top 10 is all that great. They're just not.