I have seen him go for marks 2 handed and seems to have no technique and it just bounces off his hands, surely they are coaching him on this.
I did see one time in the goal square when he was held, both arms held down, no free of course. But, it does make me wonder whether he goes up 1 handed because the other arm is being held. He does play for Richmond so we know he won't get a free if this is the case.
I would persist but he really needs to work out the marking. He can hold ground a little better but needs to improve a lot more in that aspect of his game.
DS