The thing about Dumba is he really makes some dumb plays, but you can see the potential there is sky high. He impressed me at the world championship. So did Ceci. Both of those guys play with so much swagger, you can tell they're improving and learning and will become very good players in the future. They're willing to take risks and not afraid to make mistakes.
If you look at the NHL leaders in giveaways, it's all the best defencemen in the NHL. Guys willing to try and thread the needle or make high risk, high reward plays. Subban, Doughty, Karlsson lead that category. You need defence who will do the unthinkable. You don't need defence who are too timid and scared to make a mistake so they rifle it off the glass for the icing, praying it bounces off someone first.