I like Lo Zar's suggestion, a lot!
Honestly, a PR5 that reaches his LA would be improving 0,15 each match (if the skill is lower than 15 or 13 in keepers) do you have any idea its effects in a player used in friendly, custom cup, league and wcc and international match, only 30 minutes? We are talking about 0,9 improvement each week, it's a madness! Why do we have limited ability, then?
Youth are promoted with 15 years old, are you calculating its impact on 6 seasons (until his PR reduces) just think about it....
And just to add..... don't you think that some youth players are starting to improve too fast?
I bought a 3/8/5 striker when the season begun, he is almost CA5 now, at this pace he will be CA7 at the end of season, i don't even want to imagine how fast would improve a PR7 with my training structure.... However one thing is for sure, i believe that profits are starting to get too big, the gap is starting to become huge.
IMHO, match bonuses should be lower when a player is younger than 18 years old, we are starting to have players maxed at 17 years, not even Messi were that good at that age... players become really mature about 20 or 21 years old, not before.... what do you say?