It's just not Pettersson, the entire line of Pettersson - Backlund - Nyqvist has been underwhelming to say the least. Backlund is not a typical Swedish player, he's so north south and he never does things out of the ordinary. He's such a simple center and that means the wingers - or defensemen - have to do the creative work to score a goal.
They haven't found much chemistry at all. Pettersson isn't strong enough to hold on to the puck, so he must be seen as the finisher, but so is Nyqvist. And Backlund isn't a playmaker either. I don't understand the kind of role these three players are supposed to bring as a unit. That unit needs a scramble, because it isn't working.
Wikstrand and Gustafsson are quite mediocre as a defensive pairing compared to the other four and that shows in the ice time given. Kudos to the coach for actively matching them well.