From another thread 4:
Looks like in a 4-way tie:
MSU (#3)
Iowa (#4)
Purdue (#5)
OSU (#6)
Three-way tie (with Iowa and MSU), Purdue gets the 4, MSU the 3
Three-way tie (with Iowa and OSU), Purdue gets the 4, Iowa the 3
Three-way tie (with OSU and MSU if Iowa loses at home to NW), Purdue gest the 5, MSU the 3
Purdue loses to Illinois, and they are likely the 6.
Purdue could really get some help from Indiana and Wisconsin at least for BTT seeding.