First off, all players should be aged, in main roster player can be from 17 up to like 35-40. After a player getting older, like around 27-28 they all starting to lose skills if not trained. The younger the player are, the faster they gain skills. Each season players have birthdays and age up.
Youth academy should be a long term investment, not like it is today where you throw money in to it and hope you get a player with the right stats so you can put em on the roster right away.
When you create your youth academy you choose how many players you want to have in it, from 1 - 5. These players will all be aged 13-14. You cannot add them to your roster until they turn 17, this means they have to stay in the YA for 3-4 seasons. To train your players in the YA you choose how much you want to invest, like it is now, if you only have one player and you invest 10k per day, all this money is put into the training of one player, if you choose to have more players in the YA all players gets a part of that training, so if you want to train every player for 10k and you have five YA players you have to invest 50k per day.
For this to work staff must be reworked so that it is possible to get staff easier, or if it is possible for players to gain skills some other way, may it be a open market for coaches, so that you can see eachother's bids like the transfer market, or some other market entirely. It also need to be some form of bankruptcy system that put your team bankrupt if you have negative balance for like a week so that we will start to get normal staff wages.
We also need a better scout system, you should be able to invest more money at the start then just 200. This to be able to scout better players now that you cannot buy good players from YA.
This will make the game a lot more strategic and less lucky. You "cant'" buy a really good player from the start, you have to develop and train your starting players to have a good roster or put your money and resources into scouting and get better players that way.
Hope this make sense and feel free to discuss this