I have already written about what a River-Boca means in Argentina. It´s one of the most important football games in the world, and it´s not simple for a referee to be in charge. Baldassi has large experience and looked calm and relaxed - maybe too relaxed, but that is the way Baldassi usually referees - . In Argentinian league, it´s normal to see him joking or laughing with the players. He does it even if he´s refereeing a Superclásico. It´s part of his style (and I don´t like it very much).
This one was not a violent match, in fact it was a poor football game. River didn´t do anything, and Boca played a horrible 1st half but during the 2nd, after defender Hugo Ibarra was sent-off (he insulted one of the assistants), was a bit better and could score. Baldassi decided well most of the times, and the 5 yellow cards he showed were OK.
Baldassi lost control only once during the whole match, and that was because he made 2 mistakes in the same action: when River defender Ferrari was about to enter Boca´s area, middlefielder Battaglia pushed him, clearly intentionally. Baldassi said "go on", and inmediately, River attacker Diego Buonanotte, angry because of the referee decision, fouled Gaitán (in what should have been a yellow-card action). Baldassi conceded a free kick to Boca. River players protested because he hadn´t given them the previous free kick in the area borderline - which could have also meant the 2nd yellow for Battaglia - ; Boca players also protested because Baldassi didn´t book Buonanotte. It was the only imagen during the Superclásico where Baldassi wasn´t really in control.