The problem is more related to how AI manager prioritize reputation way more than picking players because of their potential, ability or even their form. Even if a 21 years old player has higher CA and PA but has 2.5 star reputation, they will pick the 35 years old player who has lower CA and PA because he has 3 star reputation. That's a massive issue with the AI squad management. Also it doesn't help that youth player's reputation grow extremely slowly. That ends up resulting no player under 23 year being picked(unless he is one of the world's best players) after the year 2027.