To be fair, most of those defensive stats are from playing a lot of these horrible offenses in-conference. I'd venture to guess, among however few actual Big 10 against another P5 matchups there have been this season, the bad offensive teams in the Big 10 have been at or below their averages and the alleged "great" defenses have allowed far more than their season averages.
Those games will be hard to find, though, given how many cupcakes the Big 10 schools like to line up outside of conference play. OSU going to ND was an exception. IU playing Louisville has turned out to be another. MSU lost to Washington. That's about it. Not many others. Penn State sure didn't, and I would submit that is definitely the reason for their inflated defensive stats. They got gouged pretty good by OSU (and even us, relative to what we normally had been generating). Their only other "top" conference matchup so far has been...Iowa. We'll see how they hold up, with Maryland and Michigan coming up the next two weeks.