Told you, for a lot of them it isn't a matter of readiness it's a matter of service time manipulation.
They don't like just calling it that.
Lots of players, HoF caliber players, were in the majors as teenagers.
Lots of players, HoF caliber players, skipped AAA.
Was Machado a better prospect than Jackson?
Made his debut at 19, skipped AAA and had never played the position they put him at.
He turned out OK.