Take nothing away from the end result of these recent Michigan teams but they were able to benefit from a very advantageous schedule against a softer than normal B1G. It definitely played a role having 80% of the games at home and punting on having any competitive OOC games. Similar vein to the Clemson teams that were very good and proven worthy but were able to rig the system a bit to put themselves in the easiest position to make the playoffs.
They still have 8 home games next year but the rest is changing with the additional teams in the B1G, the dropping of divisions, and actually playing a real OOC game next year. The road will be much tougher to get back to the same place.