Karlsson made huge strides his defensive game this year but Sens fans will blow it out of proportion, Karlsson also has less support than the other 2 finalists, that and also his team made the playoffs. Hedman's defensive play also dipped this season, like you said probably the best crop of finalist in a long time but I'd give it Karlsson, Burns lost a lot of ground with his final 15 games.
I mean... that's certainly the *narrative*. I've seen the same issues with him I've always seen. He's weak on the boards, and he's weak in the crease. He gave up a lot of shot attempts, shots, and scoring chances.
The big narrative is "he's blocking more", but surprisingly Karlsson has always blocked a good number of shots.
His strengths are the same they've always been. Great stick, great at taking the puck away, and great in transition. But his flaws are still there and his in-zone defense was not terrific (while he did get top-notch goaltending).
And I also don't really buy that Hedman's defense dipped. First - the corresponding numbers (shots, shot attempts, scoring chances against) are all very low and by far the best on the team. Second - we had some of the most uneven goaltending in the league - it was either the goaltender putting on a clinic or it looked like Roy's last game in Montreal and no in between.
Hedman looked rough *for him* at points in the season. But I would take him at his worst defensively over either guys at their best any day of the week.
Support I suppose is somewhat fair - Karlsson and Burns both drive their teams offense more than Hedman does. One thing is for sure - you can't put the Bolts not making the playoffs on anything Hedman did though. I know that matters to the voters, but it's stupid it does.
Edit: Let me put it this way - us being reasonable about the flaws in Hedman's performance should not weigh on the fact that Sens fans are incapable of the same w/r/t Karlsson.