Perhaps the BEST B1G Forum anywhere, here at College Football Fan Site, CFB51!!!

Still starting in the simpler B1G-E:
Ohio State and Michigan are both 5-0 and obviously control their own destiny. The winner of their game can do no worse than 6-3 which means that Rutgers, Indiana, and Michigan State are all mathematically eliminated as they each already have four losses. 

Penn State and Maryland are still in the race mathematically but they have no practical chance as they would need BOTH tOSU and Michigan to suddenly implode. 

B1G-W:
Illinois and Purdue control their own destiny but all teams are still mathematically in the race, they just need the Illini and Boilermakers to start racking up losses. 

The major problem for the three-loss teams (MN, IA, UW, UNL) is that each of them already lost to 4-1 Illinois so they really need Bert to start losing.

The fighting Berts still host Purdue and visit Ann Arbor but even if they lose both of those one of the three-loss teams could only tie them at 6-3. In order to beat them, the Illini would also have to lose either at home to MSU or in Evanston. 

Illinois is gonna win it and Bert will be B1G COY.

A pretty safe assumption at this point.

Let it be noted that "even year" Northwestern only needs Bert to lose once, before Rivalry Week.

Northwestern (1-4) needs a LOT more than that. They need Illinois (4-1) to lose at least twice, they need to start winning, and they need the two and three loss teams to lose.

It's scary to think about how different the West race would be if ILL backup QB Atrhur Sitkowski fumbles 1 second earlier, late in the Iowa game, on a play originally ruled a fumble that Iowa returned for a TD, only to be overruled correctly by replay, saying the QB was down before he fumbled.

If Iowa pulls out that close game against ILL, the West would be a free for all right now,  with ILL, Pur, Iowa tied for first at 3-2,  and Wisc, Minn, Neb all 1 game back at 2-3.

Oh well, the replay call was correct,  ILL won the game, and ILL is now in firm control in the West.

It's scary to think about how different the West race would be if ILL backup QB Atrhur Sitkowski fumbles 1 second earlier, late in the Iowa game, on a play originally ruled a fumble that Iowa returned for a TD, only to be overruled correctly by replay, saying the QB was down before he fumbled.

If Iowa pulls out that close game against ILL, the West would be a free for all right now,  with ILL, Pur, Iowa tied for first at 3-2,  and Wisc, Minn, Neb all 1 game back at 2-3.

Oh well, the replay call was correct,  ILL won the game, and ILL is now in firm control in the West.

Or the Illinois apparent touchdown by Hightower against Indiana is called good and Illinois is likely 8-0

Or the Illinois apparent touchdown by Hightower against Indiana is called good and Illinois is likely 8-0

Yes, usually these things do have a tendency to balance themselves out over time.

Clinching scenarios and mathematical eliminations:

In the East:
Ohio State and Michigan are both heavily favored this weekend and if they both win that would mathematically eliminate Penn State.

The reason is that tOSU and M would both be 6-0 so the winner of THE GAME could do no worse than 7-2. Penn State could match that, but they would lose the tiebreaker because they lost to both. 

Rutgers, Indiana, and Michigan State are all mathematically eliminated already and Maryland will be eliminated this weekend if they lose and both tOSU and M win.

Short version:
If the Buckeyes, Wolverines, and Badgers all win, the B1G-E will be down to just tOSU/M.

In the West:
Illinois can clinch by winning their next two (home games against MSU and PU). If the Illini lose one or both then it gets interesting. 

After these two home games the Illini finish with two road trips. The finale is at Northwestern so they should win that but before the in-state trip to Evanston they have to visit Ann Arbor. The Illini will obviously be a substantial underdog to Michigan but it is the week before Michigan plays Ohio State so there is some chance they could catch the Wolverines looking ahead. 

What about Purdue's chances? If they win out they are in, simple as that.

If they lose to Illinois then the only thing that would prevent Illinois from going to Indy would be if the Illini fell apart and lost their other three remaining games (vs MSU, atM, atNU). 

Where it gets tricky is if Purdue beats Illinois but loses one of their other three (vsIA, vsNU, atIU).