We can start with Michigan....
Michigan has two losses, Duke has one. Duke beat Michigan on a neutral court, while Michigan beat Duke at home.
Duke should be ranked higher.
I'm not surprised by the loss at all. Duke is a team that generally follows a similar pattern. Each year, Duke will start the season by playing some scrub teams and blow them out...then a scrub team (this year, it was Rhode Island) will take them to the limit in a close game. After that, people will doubt Duke a little bit, and they will manage to blowout a quality opponent (this year, it was Purdue). Then, they lose to a relatively weak team for their first loss of the year.
It happens almost every year.