My definition of world class that I've held unto for some time now, being top 3 in your role in the world, if you're among that category for a season you had a world class season & therefore world class at the time, for eg if you asked me if bernado silva was world class in 18/19

I'll say yes, since he hasn't had a season like that in a while, he's not a world-class player but he was world-class in a certain season. When a player has at least 3 world class seasons, you can basically call them world-class at any time unless you want to review each szn

They've had one after the other, there's also those who aren't top 3 in their role in the world but have consistently performed at a high level for many years, eg ibrahimovic, David silva, Godin etc and such players can be called world-class