The difference between players who make a career as a top level player, and those that don't, is not talent, but "coachability".
Talented youngsters are typically less coachable. They don't want to listen to instructions, or train hard, or live the proper lifestyle. They already think they are good.
Hence very few talented youngsters become first team regulars, at the top level.
Of course, once in a blue moon, you get a player who is talented at such a galactic level, that this doesn't apply. They don't give a sh$t about training, or instructions, and no one really cares. The two I can think of came from Brazil and have "Ronald" in their name.
With Brewster, it was obvious a long time ago he wasn't going to make it at LFC. The club did well to offload him for a large sum of money.
Is Harvey one of the rare ones?