This is not a case of wrong or right. In the games before the tournament, Batista gaves several players a chance to make the starting line-up. If Pastore was performed (really) well in the games he played, he would've been a starter. Barcelona play with Iniesta don't they? He's an AM too. Banega did better and he and Messi clicked well so the coach kept him in the starting line-up in the following games before the Copa America. Maybe after the game vs Bolivia he'll make changes and play Pastore, who knows. The number 10 playmaker position is just something on paper in the current team, Argentina's problem is that they don't have a real playmaker (one who's of great quality of course). They just pass it to the forwards and let them do all the work, hardly any support up front from midfield. I said this before, if Riquelme was his old self/available for the NT he would definitely be playing.