Gudbransen's major weakness is his skating. It's terrible, particularly with respect to mobility and direction changes.
He's a big, strong guy that can't hit all that effectively or at least consistently, because every time he has to change direction before delivering it, he loses all the power while fighting to stay on his feet. It also takes him forever to pivot or adjust compared to the average he's facing, never mind some of the elite skaters. He's strong in front of the net when everyone is standing still, but at that point, the puck is usually already frozen by the goalie or in the back of the net. It puts him out of position on a pretty regular basis or forces him to leave a ridiculously big gap so he doesn't get caught. He has to hold back on hits because he regularly gets caught out of position when he misses, or ends up more off balance than the guy who got hit.
He's an average d-man at best. If he wants to be better than that, he needs to improve his skating.