That's an impossible judgement to make until the season is over. Remember when Auburn was #6, Arkansas was #18, Nebraska was ranked, Arizona and Arizona State were ranked... It goes on and on and on. There are no easy games in the major conferences. Some will turn out to be easier than others, but nobody can know that until after the fact.
So all anybody can do is play the teams on their schedule. You win those games, you must not be too bad of a football team.
Frankly, Purdue, Indiana, Illinois, Northwestern and Iowa are playing much better than anticipated so far. That's almost the entire Big Ten West, so again, you might be able to judge SOS when the season's over. Not so much until then, and what does it matter anyway? The schedule is what it is.
Just win.