One thing that surprised me looking at his profile on Fbref was just how low his progressive passing stats are, bottom 3 percentile. From the small amount of his youth career I saw that would not be typical of the player he was at that level, suggests that for as good as he has been there is still so much of his game we have not really seen as yet.
A few have mentioned it but at times when running back you can see he doesn't consistently have the running power yet to cope in certain situations, he is exceptional already defensively in a set shape but when it goes end to end he can struggle a bit. A proper pre season, hopefully some physical development and we could see a leap next year.