I actually have a theory that alot of pollsters didn't rank Purdue this week in the hope that Purdue will be able to pull off another win as an unranked team.
This game comes down to OSU's D-line. If they can create pressure, then they will win going away (~20ish points). If the Purdue O-line can hold up for 5 seconds each down, then Purdue has a puncher's shot. I'd still only put the odds at about 10% though.