I posted the same in the Michigan thread. Michigan is favored in every game this year. I can't tell you how unusual that is in the 21st century. It honestly may be the first time since 2000, though I may be misremembering the offseasons before 2001, 2003, 2004, and 2006. And for Michigan to not only be favored but favored by 6.5 is obviously rarer than rare.
I will say, though, that even though we're amidst an OSU golden period, with the end of the Meyer era, I'm not surprised for Vegas to be maximally uncertain or of a new mind. But that's not the same as expecting the spread to swing this far the other way.