All of them. There is no concept of team work in the Argentine National Team, and without it, you can't win anything.
A few players can carry a team long, but not cross the finishing line without the others contributing positively, and that's where Argentina lacks big time.
Every player want to do their own thing. And I'm not saying this to make Messi look better, but instead of building their team around him, the team is usually in chaos. Pastore want to dribble through several players all the time, Banega want to try his long shots, Di Maria want to dribble endlessly at the byline and launch a stupid shot or cross. Aguero want to dribble through several players and keep the ball despite of having team mates in a better position. Rojo is just......Rojo. Rubbish.
On top of that, the tactics itself aren't any better. They don't deserve to win anything unless they stop being shit heads who think they can save the World alone.