Kadri is his line's driver but he's no Tavares, Marner or Matthews so he and his line weren't scoring especially with his reduced icetime. Since Nylander has returned Kadri is putting up nearly a point per game. Teams can no longer concentrate on Kadri freeing up space because if you face the Kadri line now Nylander is the greatest concern.
Nylander beyond points has a great value in that he is able to get the puck into the opposition's end under control and he hasn't lost that.
I think it was fair to expect a slow start, at least as far as the counting numbers go. He had a late start and everybody else in the league had already been playing for two months. I think he'll come around.