Yep, that is it. In the article, McShay says Treadwell is the "premier" WR in the draft class but his draft stock is based on his recovery.
McShay must have a lot of respect for his tape if he has him above Treadwell.
Thomas does a lot of those little things make NFL receivers successful. Body control, specifically in and out his routes, and willingness to fight for the ball in traffic. Thomas won't have ridiculous numbers but has polished NFL traits.