I mean is it surprising he's sad? If getting sent back as a 19 year old rookies ruins his confidence and hurts his development long term then was he ever really going to be that good? No one knows what Wilson said to him before breaking the news. I can't imagine he wouldnt be disappointed but kids got a great career ahead of himself.
It's a good sign he is sad/disapointed (probably), somebody like a young Peter Forsberg would have been either crying or furious. ;-) Some guys may not be overly disapointed because they feel they are not good enough, William knows he is good enough, successful through his entire career, he believes in himself, thus he is disapointed.
I remember (video below) before Peter went to the NHL (when he was really young), he was almost crying after a loss and mad at the referee, he even said he wanted to punch him causing a lot of drama in the Swedish press. *LoL*. Forsberg when being told it's soon the (senior) World Championships "I don't give a sh*t, now I am going home for a shower." and you can clearly hear is almost crying. *LoL*
Story behind this: "Peter Forsberg was spectacular, he was about to win a swedish championship gold (SEL) for Modo almost by himself, Swedish hockey never witnessing such a prestigious individual performance from a young single player ever before, obviously he was disapointed when things went wrong."