I divided the MAC into halves, those with a winning conference record, and those with a losing conference record. Interestingly, all six of the top six teams played at least 5 of the weakest teams, with WMU playing all six of them, and everyone else playing 5. On the other hand, all six of the bottom teams played only 3 of the bottom teams, and each of them had to play 5 of the top 6 teams.

My conclusion is that the schedules weren't balanced, but the way they were served to accentuate the difference between the bottom half and the top half. The one team who really got a bad deal was NIU, who held their own when playing top teams, going 2-3 against five of the top 6, but didn't get a bunch of easier wins against the bottom teams. Meanwhile, the team with the easiest schedule was WMU, and even then, WMU was only 3-2 against the bottom teams, with one game remaining (EMU). Without their harder schedule, NIU might have been higher than 7th, thought not at the very top. Without their easier schedule, WMU might have been lower than 6th, but not at the very bottom.

On the other hand, among those competing for the MACC, the schedules were remarkably balanced, even if incomplete. Buffalo, Miami, Ohio, BG, and Toledo all played 5 bottom teams and 3 top teams, but that means that they each missed two of the top teams, leaving things a bit incomplete. Still, that's a lot better than, say, the Big Ten/Eighteen, where Indiana played only one game against the top 7 teams in the conference.

Based on what I'm seeing, with 12 teams, you seem to get enough mix that, in the end, the best teams rise to the top.

Supposing that instead of Ohio State, Indiana had drawn Rutgers, Wisconsin, or USC? And, it's not just Indiana. Penn State also mostly played bottom dwellers, as did Iowa. On the other hand, Purdue got to play Ohio St, Indiana, Penn State, Illinois, and Oregon. Clearly, 18 teams is too big.