Nah, he can be very good defensively, which we saw in 2017, he’s just not putting in the effort defensively this season it seems. But, we shouldn’t forget the importance of controlled zone exits as an important part of defence, and EK is 1st in the league in that department.
As usual on HFboards, we get stuck on defenitions. Sure, if "offense is the best defense" than you can argue Karlsson is good defensively. When I'm talking about defense, I'm talking about defending without the puck.
Regardless, he's average defensively at best. If he was anything special in this area, any coach would be fired for not putting Karlsson on the ice during a penalty kill or when defending a late lead in an important game. Instead, it's just "whatever".
Now imagine Detroit not using Lidstrom in those situations... The response wouldn't be "whatever". The coach would be beheaded.
Now, that doesn't mean Karlsson isn't elite. He is of course elite (or was, too early to say this year), but he needs to be outstanding offensively to make up for his otherwise average play without the puck.