Spade said:
@sabre gave you the official answer...

unofficial one (and I spoke directly to your player for this) is that he has no social life. all you make him do is train... strong curfew and what not. The last straw in the motivation breakdown was that someone stole his daffy duck socks. Now that is really hitting a new low. How can a emerging player play without his fav socks.

I suggest you find and punish the culprit and buy this player new socks (apparently he likes floral prints) to really motivate him. And please raise the curfew time from 9pm to midnight. Even young school girls have more fun then him.