Wisconsin, Minnesota, Iowa, and Northwestern all have 3 losses and only Northwestern hasn't lost to Illinois. They all have to play two of the others in the list which means that they need to sweep the rest of their games to get into the division conversation. This leaves Illinois with a huge advantage over the rest with only one loss. Purdue and Nebraska are in the wings, but Purdue can take down Illinois and have the tie breaker over Nebraska and Illinois and in the driver seat at two losses with only games against Iowa, Maryland , and Indiana outside that. Nebraska also needs to win out to likely have a good chance at the division with Purdue dropping to Illinois and another game to get them behind since they won head to head.
Illinois has been through the most to get to a division win with 2 losses. Stuff happens, Purdue has the best shot as division winner with 3 losses, if they can get past Illinois.
Purdue @ Illinois is the most impactful to the division.
Illinois @ Nebraska play important parts in tiebreakers, placing.
Iowa @ Purdue is the most likely game for Purdue to get to 3 or 4 losses.
Purdue @ Indiana is the last rivalry game to get Purdue into the muck of a weird 5-4 tiebreak system that is a mess.
Illinois @ Michigan is a game that if Illinois wins breaks all chances of someone outside of Illinois, Purdue, or Nebraska winning the division.