He is much more than he demostrated in City up to now, and I don't think it has anything to do with the position he plays. Here in River he played as a second striker a ton and had great games.
In that position he was a dribbling devil and a had a lot of through balls for us, whereas in City I haven't seen that yet. It's almost as if he's playing it too safe, not wanting to turn the ball over. He doesn't risk going one on one, or trying to thread the needle with a pass that breaks the line. I don't know if it is because of Pep's style of play or because he's not 100% confident yet.
Still, all in all, I think he's doing quite allright for a guy that isn't a certain starter and has only 1 year of experience in European football: he presses like nobody, helps in all the areas of the pitch, links up well with his teammates and has machine-like efficiency with his finishing (outside of the last game, which is the worst game I've ever seen of Julian in front of goal, and I've seen every Julian game as a professional).