College basketball this season is a tall tree that has been topped, its highest branches chopped into a brush haircut. Everywhere you look, teams that once reached for the stars have been trimmed to size. Just when a team begins to look dominant, whack, down it comes. Almost every national contender has toppled, often inexplicably. Duke. West Virginia. Kansas. On it goes. But perhaps no team has crashed farther and faster than Ohio State, which four weeks after being 11-1 and ranked No. 2 in the nation is now 12-7 and 2-6 in the Big Ten...