As discussed in
another thread, it's pretty common in OOTP for players who turn out to be very good to do poorly throughout their minor league careers, while poor players who are being sent down a lot tend to do pretty well down there. There seems to be a pretty low correlation between how players do in the majors and how they do in the minors. While this does happen sometimes in MLB, it's more often that good MLB players had a lot of minor league success.
The main probable cause I can think of is that the competition level of the minors, despite whatever settings are used, is too high. Maybe there are too many borderline major leaguers feasting on inexperienced minor leaguers. I know I'll often send down a guy who has a 30/80 overall rating and see him do very well against all the minor leaguers with 21/80 overall ratings. Are there too many good older players in the minors? Are AAA players not really good enough to be in AAA?
Any ideas on how this may be solvable?