I actually did research on the whole World Junior Championship RC deal, and for some reason in hockey as long as it was a major release and a nhl sanctioned set, players could be added to sets from the junior ranks. The final year this was allowd was 2000-01 I think and then the NHL put a stop to it. I found the article over at Cardboard Connection, I will see if I can find it. I have probably 10% of my RC list as a WJC / CHL card and then a first jersey card as well. Don't get me wrong I love the Maple Leaf but to me a good RC has them A) in their NHL unifoms and B) actually on the ice. I hate those pin-up / mugshot type cards lol.
My bad it was actually a Beckett article ...................
http://www.beckett.com/news/how-the-1990-91-upper-deck-world-junior-champions-subset-changed-hockey-cards-forever/