I disagree on Fleck playing an easier schedule.
Mason played 4 non-conference games each season to Fleck's 3, and Mason's Gopher teams caught a lot of flack for making sure the non-conference slate was well-larded with cupcakes. As for Kill, he demanded the U pay up in order to dump North Carolina from the Gopher's non-conference schedule.
Mason's bowl record was 3-4. Kill was 0-3 in bowl games.
Mason was fired, in part, because his teams lost games after holding large leads.
Mason's B1G conference win % was .400. Kill's was also .400.
I was a fan of both Mason and Kill, but Fleck is better, and it ain't close.