i understand everything except this with 5 or 0 in ending contra 4 or 9 in ending.
I might be stupid since u try your best to explain.

But i have noticed that some of my players develop fast as hell meanwhile some hardly develop anything at all.. still they are at the same age and same market value.

Does the market value give a hint about the development?

I have 2 (scout) strikers.. both are 19 years old. Both have 25 in skill. But one is valued 1,69M but the other only 460K. Why?