Northwestern hasn't beat anyone good. That's why I hate the big 10. Half of the conference is so bad that it makes for easy wins for the average teams and it makes them look good instead of average. But the media keeps pretending that they are a great conference.
Add to that the fact that they don’t play everyone so certain teams can get lucky and avoid the decent teams, beating a bunch of MAC level teams in a “P5 conference“ and thinking they are something special.