I think it's important to point this out because I think the reason this year is actually different than it usually is. The Big Ten used to do poorly in bowl season because too many teams played an anachronistic style and were unprepared to stop pro-style and spread offenses. I no longer think this is true across the board as many teams have (to their credit) attempted to modernize a bit. This year the Big Ten was bad because of a mix of down years for typically solid programs, and a few injuries.
1. First and foremost, Michigan is just plain bad.
2. Michigan State overachieved in winning a share of the Big Ten Title. They were close to losing several games to bad teams, and ended up in way over their heads in their bowl game. It happens sometimes.
3. Penn State had a down year, and only narrowly lost to Florida, which also had a down year.
4. Poor Northwestern lost their good QB, and played a feisty game anyway.
5. Wisconsin played a good team and barely lost. It happens.
6. Illinois and Iowa actually won their bowl games, but as lesser Big Ten schools (in terms of record) no one cares. Iowa decided to show up after playing terribly down the stretch.
A lot of individual things went wrong for the Big Ten, but I don't think there is anything systemically wrong anymore. I suspect that after Michigan gets Harbaugh they will rebound (eventually), that Penn State should develop into a stronger team, and that OSU will keep cheating their way to national prominence.
1 hour ago