Is Dennis Gates going to get Tiller to play tough and break his bad habits? The Hall of Fame HC (who has a track record of doing it) couldn't.
Development isn't happening unless the bad habits are broken.
Unrelated fact: Dawes is only seven months older than Tiller.
For a team in a win-now mode (KU), taking the kid with multiple years of proven production in the B12 with a style that doesn't need to be changed is an upgrade.