One of the things that makes soccer unique in the sports world is the main thing the failed Super League tried to change: the best teams and best players in the world rarely play against each other.
Of course, that's slowly -- or suddenly, depending on your frame of reference -- changing as the Premier League continues to gobble up the best players and best coaches, but just take the top 15 from UEFA's club coefficient rankings. You've got four teams from England (Manchester City, Chelsea, Liverpool and Manchester United), four from Spain (Real Madrid, Barcelona, Sevilla and Atletico Madrid), three from Italy (Juventus, Roma, and Inter Milan), two from Germany (Bayern Munich and Borussia Dortmund), one from France (Paris Saint-Germain), and one from the Netherlands (Ajax).
This creates a special kind of uncertainty. In other sports, we generally know how good each team is because they all play each other and the same opponents, all season long. In soccer, we can only sort of tell how Manchester City compare to Real Madrid until they play each other ... and then City win 5-1 on aggregate.
It goes in the other direction, too: The best team in the Premier League should wipe the floor with the third-place team in Serie A ... and then Inter Milan hang tough for 90 minutes and outshoot City 14-7 in the Champions League final.
Now, take that team-to-team uncertainty, multiply it by 1,000 and you've got the player-to-player uncertainty. Is it harder to be a center back for Bayern Munich, or Manchester United? Is the best winger on Atletico Madrid equal to Borussia Dortmund's star wide-man? And how the hell do we even begin to contextualize what it means to perform for PSG?
Put another way, we don't really know what it means to be "world class." Everyone says it, using it as shorthand for, uh, well, something -- something like "quite good" or "one of the best." But despite all of the uncertainty about how teams and players compare, let's try to define the phrase -- and then figure out who deserves the tag.