I've always said that the best team in the division should win THAT DIVISION. Cross over games should serve as a tie breaker.
If NU wins every game against division rivals, but goes 0-2 against an undefeated Mich St by one point and a scratch your head loss against Rutgers (it happens every year) but Iowa's only loss is to NU by 21 points (with a much easier cross over schedule) who is the better team? (OK, this year isn't the best example for NU)
So lets go hypothetical: Team A runs the west, but loses to OSU and MSU, both by one point in OT. Team B loses to Team A, but barely beats Indiana and Maryland. Best team is obviously . . .Team B!