I have no idea.
In one of my team i have a ST from academy that scored a lot of goals 1vs1 i teached him the SA 1vs1 and he started to miss them more then before.
My DML ML AML I have teached him the playmaker SA and he scoring goals like Never before, he is current my top scorer. I dont know If it was because of SA, dosent make sense to me, or just because this season he is in top form, i have to wait one more season to know.
If only Devs could explane a few things.