basicaly im asking how much average 1 skill point (1 cone) increase the value of player in money

i have a 18 age player 15 quality (14 - 16,2 - 16) and each cone(1 skill point) i put in him he get 10 k (he is 750k atm and he went 780 after 3 i put him)

but i have a 19 years old player 20 quality (23,8 - 18 - 19 ) at 650 k and i put in him 4 cones(skill points ) and he didnt get any increase in value he stayed 650k

im level 2 manager season 2 level 2