I don't see Ecuador capable of winning Argentina. Now Paraguay should win with some ease, which is in the penultimate position. That's why I don't see great difficulty in Ecuador finishing the group in third.
He would only drop to fifth if he loses both games and Peru wins every game. But the game against Uruguay will not be easy.
Since Peru is playing Uruguay in the next round, there is no mathematical possibility that both of these teams will be able to overtake Ecuador. Peru could overtake Ecuador, but in that case Uruguay would only be able to score the same number of points with Ecuador. Chile may be on par with Ecuador in points (instead of Uruguay). But all these teams have a negative goal difference, while Ecuador has +10. This is the first parameter that is taken into account when points are equal, so these teams have no chance to move Ecuador below fourth place.