When a coach takes over a football program that has struggled for years and in a short period of time turns his team into a contender, it elevates the conference as a whole. Jerry Kill did just that at Minnesota and it has been very good for the Big Ten.
The more contending teams there are in the Big Ten the stronger the national perception of the conference is. This improves the rankings of teams and increases the chances of an Ohio State or Michigan State making the playoffs with one loss. It can even help a team get invited to a better bowl game than they might have otherwise.