Wow. Can you give me empirical evidence that the NHL is the best in the world? It probably is no doubt, but top level leagues in the same sport are a LOT closer than you make it seem. In international exhibitions NHL teams only have a 2-1-0 advantage over KHL squads, and none of those games had a goal differential higher than 2.
Who is the 'major league' of soccer pray tell? If you say English Premier League you'd be dead wrong (either Bundesliga or La Liga). What about our Fury? Division 2 in North America would seem to be minor league, but there's a chance to play teams in other levels of the sport all the time (witness FC Edmonton and Montreal Impact this month). Does that change their 'minor' league status? Just because a league get's a lot of coverage and has the most money does NOT put it in another category above any other. That's silliness.
Pro = paid to play as a profession. Hence pro.
I can't speak on soccer because i know nothing about it. (Should have worded it better.)
I was mainly talking about the 4 major sports here - baseball, hockey, basketball, football.
Almost all the best players play in MLB, NBA, NHL, NFL.
Of course, if you were to have other teams from other leagues play vs. the best they could win a couple times, but the majority of the talent are in the leagues above mentioned. And if they aren't there yet they will be trying extremely hard to reach the goal.
All CFL players want to play in the NFL, all AAA/AA/A/Japanese players want to play in the MLB, All players world wide in basketball leagues would like to play in the NBA, if good enough.