My guess is that winning percentage at home influenced the rankings as well as attendance, and that they factored in more than just the last few years. Here is the home winning percentage for MAC schools since 1960:
Toledo .711
CMU .699
Miami (OH) .677
BG .657
WMU .642
Ball State .599
NIU .588
Akron .556
Ohio .526
EMU .440
Kent .434
Buffalo .425
If you want, you can pick your own years, and s
ort the data yourself . Here is just the Solich years
MAC 2005-2011 Home winning percentages
WMU .737
NIU .725
Ohio .692
CMU .629
Toledo .610
Kent .462
Ball State .447
Miam OH .432
Akron .421
Bowling Green .405
Buffalo .385
EMU .333