I'm not concerned about the DE%. There won't have been many today that had much if anywhere above 50%, it was a win ball, hack if forward off the boot type of game. No skill, just see ball, win ball and get it forward.
The key, as you say, is the ball winning ability. There were concerns about how he'd go with a slight body against men, well he did pretty bloody well today in a heavily contested game. I'd say that concern is a myth. The guys he was playing against today weren't 19/20 year old draftees that aren't physically ready yet for the AFL, these were mature, big body mid to late 20's mids he was playing against.
Big tick for him today IMO. Would be very happy to take him with our 1st pick.