He actually can improve quite a bit, my two legitimate areas for him to work on are
- Finishing, he has missed some very easy chances this season (he would easily be in Kane numbers if he took more of his easy opportunities)
- Control a game, he still fades in/out, he has to impact games more than "just" popping up with a goal/assist.
No complaints, 20 with a ton of promise and good contribution, but you can definitely see where he should be spending coaching/training ground time.
If he fixed those two things, he'd be in the top tier of world players.
p.s. huge credit to him for passing the ball to Son for the goal, minutes after Son didn't to him ...