Academy
In example:
From 15-17 higher development ratio but unable to join main team.
From 18-20 medium development ratio.
From 21 to 23 no development ratio.
At 24-25 retirement with a possibility to add as a staff member.
Of course each individual player would have different learning cruves. in example Faker would improve even when he is 22 or so.
-Dertheia