We're only 3 weeks into conference play, and the picture is still a little cloudy. I'd like to clear it up a little, and start to get some insight into who might win this thing. So in looking at all of the upcoming games that the top teams have against each other, I'm going to make things simpler by assuming that a ranked team will always beat an unranked one. Of course, that leaves possible dark horses like Purdue and Northwestern on the outside looking in. And since this is the Big Ten, if something crazy happens like Northwestern upsetting MSU this week, all bets are off.
With that said, we are left with four current favorites to be Big Ten champions. Of course, they are Wisconsin, Iowa, Ohio State, and Michigan.... State? That's right, a new power has arisen in the Mitten! Among these four, there are only three games left between them, and they all happen to take place in Iowa City. So let's look at all the ways that those games could play out, and figure out who needs to do what in order to win. Because as we all know, in college football, there can be only one! Wait, um, that's not right.... let me see, co-champions, head-to-head selection, aha.... There can be at most three!
Suddenly, there is a clear front-runner in this race. Of all the teams, Michigan State is the one that has the shortest path to victory. The championship really is theirs to lose. In fact (remembering our assumption of no upsets), as long as they win at Iowa, they can't be touched. They will be Big Ten Champion outright.
Interestingly, even if they lose to Iowa, they can still be champions, and get the automatic selection for the top bowl bid. That would happen if Wisconsin beats Iowa this week, who later goes on to beat Ohio State. In that case, MSU, Wisconsin, and Iowa would all tie with one loss apiece. Iowa would be dropped for its additional OOC loss to Arizona, and then MSU would claim the head-to-head against Wisconsin. So Spartans, you'll want to root for Wisconsin this Saturday!
What's more, even if MSU does lose to Iowa, then as long as Iowa drops at least one game, MSU is guaranteed at least a share of the championship. Although, if Iowa loses to OSU so that the head-to-head scenario with Wisconsin doesn't happen, then the co-champion to represent the Big Ten is selected by BCS ranking. In that case, MSU probably would lose the top bid to either Wisconsin or Ohio State, who began with higher pre-season rankings, and whose one loss came earlier in the season.
If we give each of the three games against each other even odds, then ignoring upsets, MSU has a 50% chance of being outright Champion and an 87.5% chance of being co-Champion.
To sum it up, the only way that Sparty doesn't get a share of the championship is if Iowa goes undefeated. That brings us to....
The only way that Iowa can claim the Championship is if they go undefeated, beating all three of MSU, Wisconsin, and OSU. Then all the other Big Ten teams would have at least one loss, while Iowa's only loss would be out-of-conference. Anything less than total victory, and Iowa's OOC loss does them in in the tiebreaker.
On the upside, all three of those games happen in Kinnick stadium; and, if they win them, they claim the Championship outright. Their fate is still in their own hands. Unlike....
The Buckeyes' fate is not in their own hands. Their only hope is to be co-champions, and then be selected by the BCS in the tie-breaker. The only way for that to happen is if they beat Iowa, and Iowa beats Sparty. Again with even odds and no upsets, the odds of this are 1-in-4.
In that case, Iowa will be dropped from the tie again because of their OOC loss, and the BCS will choose between one-loss MSU, OSU, and perhaps Wisconsin if they beat Iowa too.
On the upside, the pollsters do like Ohio State, who was a heavy favorite coming into the season. They would probably get the nod.
Poor Wisconsin has only one loss, and it was in an early away game to the top contender no less, but they need everything to go just right to have a prayer of representing the Big Ten.
Like OSU, the Badgers require a BCS-brokered tie. Unlike OSU, not only do they have to beat Iowa, and hope Iowa beats MSU, but they also need OSU to beat Iowa too. Otherwise, it comes down to a tie between MSU, Wisconsin, and Iowa, and MSU wins the head-to-head. Wisconsin needs OSU to beat Iowa so that the tie is between MSU, Wisconsin, and OSU instead (1-in-8 odds). Then they need to hope that strength-of-schedule and having the earliest of the three losses pushes the BCS to pick them over the other two.
I'm sorry for ignoring the others up to this point. Purdue is undefeated in the conference so far, but they didn't start the year very well, and all of their toughest games lie ahead of them. Northwestern's toughest games lie ahead as well, and in addition, their one loss was to Purdue. Illinois and Michigan have both looked good at times, but they also have two losses already (albeit to the top 3 teams). A lot would have to happen for them to get back into serious contention.
Still, as I wrote above, anything can happen in the Big Ten, and I wouldn't be shocked if one of these teams threw a few wrenches into the works.
Edit: For a more thorough take involving more teams, more numbers whizzing around, and less assumptions, be sure to also check out this post by Jonathan Franz!