you wrote that if a FT at 18 yo with 80% Q, at 19yo we will have 68% Q and same market value
which is tottaly wrong...
I think he meant that a 18 yo with 68% quality will have the same market value as with 19 yo 80% quality (so 1 year more and 12% more on the same player is the same market value). It can be, but I don't know the actual numbers.