I think his strength is acceleration, but right now, he can't go past his relatively low personal speed limit. You see it in the top-speed/average speed stats. Stamina is an issue that could be fixed, IMO.No amount of working with a fitness coach will make him sustain his speed over a further distance. Unfortunately you either have the stamina or you don't.
He is young, though, so hopefully he can significantly improve in all aspects of his game.