In my opinion, this is a biased statement - Xavi and Iniesta made the greatest contribution to the team. If you remember Xavi and Iniesta won the 2008 European Championship, then the 2010 World Championship and then again the 2012 European Championship - the greatest achievement. They did it without Messi, and without them, Messi himself failed at the 2010 World Cup and then at the 2011 America's Cup.
what you say is true
but only European players and teams play in the European leagues
teams like Brazil, Argentina, etc do not play
in your opinion is it a good approximation?
In my opinion it is not a good approximation
This is an approximation not to the European leagues but to the games of the national teams. If you noticed, I mentioned the America's Cup, where European teams do not take part, but players from South America can prove themselves. Messi had such an opportunity in 2011, but he did not use it, just like in 2010 at the World Cup.