He wasnt definitely very good there though. Quite ok in most games, and even good in some, but definitely not very good in general.
I guess we can say he was very good compared to other 1st line centers we had after Aho and Teräväinen in U20s.
Kupari was a lot less hyped than Kuokkanen was and he clearly outplayed Kuokkanen in there in almost every aspect of the game. And before Kuokkanen we had Aapeli Räsänen who just doesn't make the cut for 1st line center in U20s but you can't really blame him because we didn't have anyone else back then.
Kupari could have had couple more points based on the chances he got and sure, Heponiemi was the main playmaker in that line but I'd give credit for Kupari for being relentless throughout the tournament which showed in like 10 drawn penalties. In the faceoff circle he was among the best in the tournament
In my opinion, Kupari was everything you could have expected from him if you respect what his strengths are.