I'll be honest, Purdue is a lower level big ten team. Minnesota is a lower level team, even with all of their fancy history in football. Illinois is a lower level team, iu is a lower level team.
Your mid level teams, truth be told, are iowa and Northwestern. MSU is upper mid level, with Wisconsin. Northwestern shows that a lower level team can absolutely move to the mid level with good coaching. Iowa shows that too, along with WI.
Tiller had purdue clinging to that sought after middle of the road, Mallory had iu right there, too.