I thought the Western Canada Cup, RBC cup and WJAC were pretty good places to look to find weaknesses in his defensive game. It's important to note that there were only 3 other NCAA committed players in the entire AJHL outside of Brooks (16 teams in the league, BTW), so he spent the entire season playing against mostly guys whose futures lie in CIS hockey or lower. He looked solid defensively in the AJHL, but when he played Penticton and Battleford and Coubourg or international teams at the WJAC you could see him struggle at times without the puck. And yeah all defense prospects struggle at times, but there aren't too many #4OA picks who even get the opportunity to struggle against a team like Battleford.
Again, on the puck he's a magician and as good as anyone in the draft--seriously--but go back and watch those games if you don't think his play away from the puck deserves scrutiny.
And as good as his juggernaut team was, they lost out in the RBC Cup final to a Cobourg team with only 3 NCAA commits. Obviously anything can happen on any day (and Cale had two points in the game), but I'd want to see my #4 pick absolutely dominate that level and he didn't.