The Top 4 were the top 4 because they also, generally, took care of business against the non Top 4 teams:
Miami slipped up against Toledo
Ohio took care of business
BG slipped up against NIU
Buffalo slipped up against WMU
WMU slipped up against CMU and NIU
NIU slipped up against Toledo and Ball St
Toledo slipped up against Akron
You can't look at this data and not conclude that the two teams playing in the MACC game are the two that deserve to be there. Miami won all games against the top 4, and only screwed up once. Ohio was 1-1 against the top four, and never screwed up at all. While WMU was also 1-1 against the top four, they also screwed up not once, but twice. Neither BG or Buffalo beat any other team in the top 4.
There will indeed be years where the current system leads to the wrong teams playing in Detroit. For an extreme example, look at who Indiana played, and they could easily have been in their championship game. This year, however, the MAC system worked, and the two teams that belong in the championship game are the two that are there.
Consider, that if the MAC still had divisions, the Championship game would be 7-1 Miami versus 4-4 Toledo. Who here thinks that a team that was destroyed by Ohio, and which lost to Akron, belongs in the Championship ahead of Ohio?
“We have two ears and one mouth so that we can listen twice as much as we speak.” ― Epictetus