I agree with Bwar on MSU, at least for now. Yes, MSU has lost two of their last three, but I also think that they have played three of the top five teams in the B1G in their last four games (UMD, tOSU, M).
I *think* that at least Maryland is good enough to be in tier-3 but, like Bwar, I have my doubts about PSU and MN.
Perhaps:
1) PU, MSU
2) tOSU, M
3) UMD
4) PSU, MN, UNL, UW, IU, NU
5) Iowa
6) RU, ILL
Tier-4 *feels* like it has too many teams, but I don't think any of them look good enough to join Maryland and I'm not sure which ones should drop.