It's ironic to me that B1G is 4 of the top 5 but I don't think it's objectively a great year for the conference. Michigan and Ohio State last year were better than any B1G team this year. Oregon may be for real but they're a speed/finesse team -- I could see them getting clocked by physical upper-mid SEC team, say an Ole Miss or a S. Carolina. Ohio State really should have beaten them and tOSU is better now.
PSU is a good solid team, and improving, but their overall athleticism and depth is more like a top 10 team than a top 5 team - you saw that last week against Ohio State. Indiana, happy for them but they are an imposter, they haven't even played a top 25 team yet, they'll be unmasked at the Shoe next week.
And then all these teams that are perennially or occasionally in the top 10-15 are just down this year. Michigan, MSU, Iowa, Wisconsin. And the lower level is pretty low. Wasn't that long ago Northwestern had enough talent to beat good teams on a good day -- those days are over, they just have nothing now. Purdue and Minnesota used to make noise but not this year. And the PAC, aside from Oregon -- UCLA is UCLA and USC and Washington are both in transition; they're going to have to retool significantly to compete in B1G stadiums.