Selling your players to a football agent will immediately give you

60% Value for 18y.o
57,7% Value for 19 y.o
55.4% Value for 20y.o
53.1% Value for 21 y.o
50.8% Value for 22y.o and so on... decreasing around 2.3% for every year untill you get to 28% Value for 32 y.o player
That's why we won't be seing Free agents anymore.