Individual skills being allowed to have a negative, and therefore hidden value is the problem.
I started playing in 2015 so I don't know how the old system that Khris writes about worked. But a limit of average quality between the 3 areas of training (attack, defence and physical and mental) does sound like a better system than the one we have today. 20%, 30% difference at least gives some scope for players to have some individualism and not leave every team in every league on every server with exactly the same player skills.