I was in Italy the year Ronaldo de Lima transferred to Inter from Barcelona, and the Italians were always keen to show that they could bring down his goal average, because they maintained that the marking in Spain was not good enough. Ronaldo played exceptionally, even in his first year in Italy, which was unheard of. Most foreigners took at least a year to adjust to playing in Italy. He was so good that even the Italians, who are normally difficult to please, began calling him 'il fenomeno'. In my opinion he could have won the Serie A that same year, but for some dodgy refereeing. The way he went past the likes of Maldini, Nesta and Cannavaro was unbelievable. However one could still see that Ronaldo found it much tougher, because the Italians really know how to defend, both individually and as a defensive unit. Goals in which he made multiple dribble became very rare when he was in Italy. On the whole I think he passed the test with flying colors. The Italian experience, I think, helped him to handle difficult matches because he was able to play a lot of them (against Milan, Juventus, Parma, Lazio, Roma, Fiorentina...) I also think that it helped him subsequently in his career, at club level and national level. Also in Italy it was not uncommon that a superstar was allowed to touch the ball only a handful of times in 90 minutes. They were very good at shutting down top players.
Messi is a special talent, who reminds me of Ronaldo de Lima. When he has the ball on his feet, people hold their breath expecting magic to happen. He has been able to play consistently at a high level, in a team that has also allowed him to play at those levels. I was kind of disappointed with his WC 2010 performance because I wanted to him to do well. Its always a great story when a superstar like Messi does well in a big tournament like a WC. He came very close in 2014 , but still he did not shine as a player. I suspect Messi's problem in the national team is largely mental. Playing in a machine like the Barcelona team is almost perfect for a superstar like Messi. I have the feeling that when he goes to play for Argentina, there is a sea change in team quality, even though Argentina has great players too. I feel that if Messi goes to a team like Chelsea, Man City, Juventus or Mann U, he will develop mentally because he will have to dig a bit deeper to produce great performances. Those teams are still formidable but they are at least a step below Barcelona. It will help him suffer a little bit more because those teams are not always attacking powerhouses, unlike Barcelona which controls the rhythm of play in almost every match. If he gets used to playing difficult matches in which he may not touch the ball for long periods of time, he will learn how to be more efficient in the national team as well.
