Funny how a guy who can't make our defense goes elsewhere and is suddenly good. I suspect the same will happen with Gards. The Leafs defense is fine. The issue is they are all Carrick type D but better (Strong, offensive puck movers) and Carrick was the worse of the bunch. Leafs are desperate for strong shutdown crease clearing cycle stopping D so Babs played anyone like that over him on the bottom pairing (like Polak).
The issue isn't lack of talent it is lack of ability to execute the system. Either the coaching staff suck at explaining the system to the players or the players aren't smart enough to execute it. However given their abilities and ability to follow the system from the blueline through the offensive zone, it must be a system issue.
Like I said before, Carrick was going to become a Stralman type. He would find a fit and be a very good top 4 D for someone. Sadly in Toronto he would never be given that chance simply because the need for a different type of player on defense was greater than the value Carrick brought by being a better player.