Since expanding and bringing in the likes of Nebraska, Rutgers, and Maryland, the Big Ten has been trying to figure out the best approach for handling conference football games. The first attempt was to create a Legends and Leaders divisions (which made absolutely no sense), but regardless of the terrible approach to naming, the general alignment of schools didn’t make sense. The Iowa football team lost its rivalry game to Wisconsin, and geographically the teams were a bit more dispersed.
The original breakout of the divisions was were as such:
Legends: Iowa, Michigan, Michigan State, Minnesota, Nebraska, and Northwestern
Leaders: Ohio State, Purdue, Penn State, Indiana, Illinois, and Wisconsin
Competitively speaking, that breakout may have been on to something, but when Rutgers and Maryland joined, realignment needed to happen again and the Big Ten went with a more geographically cognizant (and much easier to remember) approach, which is what we have today.