I went back and looked at all of Dylan's previews, noting the Pomeroy predictions for each Big Ten game. They predicted:
Michigan by 11 over PSU(check)
Michigan by 4 over Minnesota(check)
Indiana by 12 over Michigan(check)
Wisconsin by 7 over Michigan(nope...79% chance of badger win)
Michigan by 5 over Northwestern(check)
Michigan by 4 over Iowa(nope)
MSU by 4 over Michigan(nope)
Purdue by 4 over Michigan(nope)
You might as well flip a coin.
If you look at the actual scores, they're all over the place, ranging from Wisconsin(underpredicted by 25 pts) to Iowa (overpredicted by 20) you come up with Pomeroy underestimating Michigan by about 3.5 points/game. (I expected a larger number too, but that Iowa game really knocked the average down).