I just think there comes a time in player development when potential and ability as a kid can only progress if combined with some other attributes like intelligence, footballing brain, determination.
Ross Barkley never struck me as having those latter attributes to push on to next level.
And there is a few players I could call out for lacking 1 or more of those attributes to push on. Iwobi doesn't seem to have much footballing intelligence to his game which means his end product isn't good enough.
Then on the flip side of the coin. When you see interviews with Calvert-Lewin... he seems to have all 3 of those latter attributes which stands him in much better stead to progress his talent and make it to the next level.
And even the most recent Niels Nkounkou is showing more intelligence to his game on the pitch which gives me much greater hope of him making it big.
Some players just understand the game and are keen to learn, develop, and improve, some are lazy with their talent or lacking the intellect to apply it into something more
Just my 2 cents