Iowa places well in Chicago. Frankly better than it should. Not that it's a bad school, or anything. Even if with go with your top 35% statistic, that truly isn't awful. I promise you that 35% of Loyola-Chicago or SMU grads cannot get biglaw in Chicago. I don't even know what SLU is, but if that is St. Louis University, then the top 35% aren't getting biglaw in Chicago.
It's possible that SMU places better into Dallas biglaw than Iowa does into Chicago biglaw...possible, but a lot of Iowans go to the Twin Cities as well.