Relying on bowl games to determine which conference is best is fucking stupid, especially given the top Big Ten teams are playing virtual road games a lot of the time.
Michigan playing in Florida State's back yard (without 2 of their 3 best players most of the game) and losing in the last second isn't really something to be ashamed of. Iowa playing in 85 degree weather in Florida against Florida. Penn State playing 15 minutes outside Los Angeles against a team..... wait for it..... from Los Angeles. Yeah, no advantage there or anything.
Again, have these teams come north and play the game at Soldier Field in 35 degree weather and see how it goes for these Southern and West Coast schools.
It isn't the ultimate determining factor, but don't pretend there is no disadvantage for Big Ten teams every single bowl season.