It is rare but if you have a 20-22 year old in AAA with very good talent and current ratings (some Good/Brill talent combined with 'filled out' numbers in all area's) you actually risk stunting his devel if you keep him in AAA for too long. Sometimes when these guys flame out they do so in grand fashion and it's pretty depressing
. This is one of the more interesting decisions in the game - you want them to devel up to the max that AAA will allow them to devel while at the same time not "start the clock" on his years before free agency. Fortunately the game gives you quite a bit of time to make this decision.
BTW a good way to think about devel is considering the MLB roster as AAAA for young players - they will rarely peak in AAA.