I made a mistake to over-train this player. If a more sp is added, he will be promoted to next star. My team has history of auto-adding some sp even in PC version. So I am afraid that I will be very likely to find him promoted in next season day.
Luckily, no sudden auto-assign sp to this player before I sold him. But I hope receiving more for a 19 year old 1 sp away from next star player. The selling price was not even matched his market value.