The weekly roundup gets somewhat less enjoyable with each loss, but here's the chart nevertheless. I've incorporated Seth's suggestion of including last week's rankings for comparative purposes. Last week's rankings are indicated with a less opaque icon; if you can't see it at all, it's because the ranking hasn't changed much at all.
Click to embiggen:
So, we seem to have a four-tier B1G:
Good teams: Ohio State, Wisconsin, Michigan State
Above-average teams: Nebraska, Minnesota, Michigan, Northwestern, Iowa, and Indiana is in this group, too, despite their schizophrenic nature (excellent offense, abysmal defense).
Below-average teams: Illinois, Penn State
Horrible teams: Purdue