I've just been watching some videos of him on youtube from the recent u20 world cup and I have to say this guy is still very, very raw. I'd even go as far as to say he probably won't be a Chelsea player any time soon if at all.
I know judging players on youtube is a bit silly but these show all of his touches in the games and I have to say that isn't very impressive at all. His passing isn't that good, technically he is about average and he is very greedy and shoots when there are better options. He's going to have to do a lot of improving in the next few years. I think he will be a Vitesse player for a long, long time.