I don't have the facts at hand to support this statement, but my observation is that the US didn't become a perennial contender for international tournament honors such as the WJC and Olympics until the talent net was spread wider to cover the non-traditional hockey areas. Perhaps with the a larger pool of talent, hockey is attracting a better type of athlete rather than just hockey players?
From observation, a fair amount of hockey players in my area are products of families with high disposable income thus they get very good training and travel extensively. So, teams from all over travel to the same tournaments and can establish the measuring stick against teams from traditional hot beds.
I don't follow the results closely but the general them isn't that these teams go to Canada and get spanked consistently. And clearly some of their players are on par.