For me he is going through the same period of readjustment that Mane had to deal with last season, but multiplied twofold because of the heights he's coming down from. Teams are double marking him and giving up space to T A-A and to the CMs. So he's getting less of the ball and in worse positions and is overcompensating. He just needs to settle into the reality that this season he may well be a very good player in a world class team, whereas last season you could well argue that it was the other way round.
I don't think he'll ever hit the goal-scoring feats of last season again. As good a player he is he is not a Messi or Ronaldo. But that doesn't really worry me as I'm confident that the vast majority of goals that drop off his total will be picked up by other players.