I watch a lot of hockey. Setting my bias aside, Dahlin along with Morrissey up in WPG are the best defensemen I've seen play this year. Both are solid both ways and have elevated their team's play. Karlsson is wicked with the puck, but he isn't even noticeable defensively and doesn't elevate the team.
Karlsson is a -1 for the year even with all those points, Morrissey +8, Dahlin currently sits at +22. It should be his to lose. But...points...Karlsson.