''bad''? What do you mean, below average or not even NHL caliber? Either way you're wrong.
First of all, he plays 28 min a game and is 23 years old. Do you expect no mistakes? Please. Even Lidstrom would make mistakes logging those minutes on this team. This year, EVERYONE on the team is bad defensively except for Turris. Everyone looks ''bad''. That would make it extremely hard for Karlsson to look good, no?
Second, no he hasn't been good defensively this year, but he's been average overall. I don't care who you are and what amount of points you put up, you don't get 28 min if you have 6/7 D level defense (i.e. Corvo).
Third, he's been good defensively during his career. He was one of the best defensive players in the league last year. In his Norris year, he was above average for an NHL defenseman and got the toughest matchups on the team.
So please, spare us the lies.