USA's world class players since the Mosconi Cup began have been in reverse chronological order:
Shane
Archer
Strickland
Sigel/Varner (about same age)
5 players. I may have missed a couple. The time span between Shane and Archer was large. Even larger, no one has come up after Shane, which is now 18 years later! (2007, his breakout year).
wouldn't you say corey filled that spot between archer and shane? corey, JJ, schmidt would all have been reigning US open champions at some MC they played. i kind of get what you mean by world class in terms of WC winner, or sustained world class level, but some guys had a couple of years when they were at that level.