The Kansas City Chiefs have a few offensive linemen missing so it caused them to do some mixing and matching at Monday afternoon's practice.
As Josh Looney of KCChiefs.com points out, Niswanger spent some time as a reserve guard with the Chiefs in 2007. He also started at least one game along every spot on the offensive line for LSU.
There's no word of a Lilja injury. My guess would be that it's just a veteran getting a day off.