I don't disagree with the general sentiment of your post (i.e. that at 18 he isn't ready to come in and boss PL midfields). I am wondering, though, since his height is such a contentious point, where you got this 5 foot 3 measurement from. He's reported at 5'3" on ESPN and Wikipedia, but they're getting those numbers from the squad list of the 2017 FIFA U-17 World Cup. Surely it's possible, maybe even probable, that he's grown in the last two years? I don't think he'll ever be even average height, but it is possible he hits Iniesta height some day. I didn't hit a growth spurt until late high school and into college, and my SO even grew another inch (to hit 6 feet) in her second year of college (so 19 or 20).