it starts from the very top.
1. The Argentinian FA is absolute crap.
2. Management is crap.
3. and now most of the players are crap too, not crap but not good enough, not experienced enough.
Add all those things up and you get a crap team, Messi is the only thing holding that team together, people criticize Messi so much, but they don't realize that without Messi, Argentina wouldn't even be making the World Cup or the Copa America.
People say oh they have Di maria, they have Aguero, where was Di maria, where is Aguero, they are either injured of they don't show up to the game, why is no one is blaming them, instead they blame the only guy who actually does something for Argentina.
Messi does all the same things that he does for Barcelona, if you watch the games you can see it, the difference is he doesn't have Barcelona type players at Argentina to contribute, Messi has to both create the chance and score it because he doesn't get much help. Football is a team sport, you can be the greatest ever but you still need your team to help out, no player however good he is can win 1 v 11,