So now there are only four teams in the Leaders Division that can get to Indianapolis on Dec. 1 for the right to go to the Rose Bowl (or possibly the BCS title game). And with all due respect to Indiana, the Hoosiers are not a viable contender after failing to win a single game against FBS competition last year. So, barring an utter miracle out of Bloomington, we are realistically looking at three possible teams that can win the Leaders: Wisconsin, Illinois and Purdue.
This is why Northwestern was upset. There are literally only four teams who are qualified and probably no more than three have a shot. Meanwhile the other division has at least two preseason top 25 teams and a third borderline one.
If you are interested in a dark horse in the Leaders though, Purdue seems like the best option. They have all kinds of experience returning and a bunch of potential talent. If Wisconsin stumbles they will have a chance.