Experience and training is all a pilot has.Superior training can offset a shortfall in experience but only to a certain extent.Training determines skill level and theoretical knowledge,both important ingredients in a pilot's make-up.However,you cant train cognitive judgement and airmanship.This only comes with experience.
Can a pilot with 1000 hours jet fly as a 737 skipper?Even if that pilot was mature beyond his years and had received excellent training then he would still be unsuitable for jet command in my opinion.I know such pilots do exist but todays aircraft are so reliable and automated that the dangers of premature promotion dont reveal themselves.