Ruiz knew what a Brazil-Argentina was. In fact he had been the referee in the last WC preliminaries match in Brazil, 4 years before. He tried to control everything, but apparently he decided to keep that control by not using cards during the first part of the match. The game was a bit problematic, with harsh actions: at 2nd minute Coloccini should have seen a yellow. Ruiz decided just to talk, but ... it had been a hard foul, and should have been punished more severely.
Both teams contributed to make an interrupted game. Lots of fouls. Ruiz stopped actions too often, though sometimes he didn´t have other options. He showed 6 yellows, almost all of them correctly, but he missed 2 or 3 more yellows (Brazilian defender Juan was forgiven by Ruiz twice, when he was already booked). Ruiz also missed fouls; there was a controversial action during the 1st half, when Argentinian GK Abbondanzieri slightly slapped Robinho inside his area. Ruiz could have whistled, but the slap didn´t seem to be important enough to knock Robinho down or interfere with his movement. Ruiz didn´t lost control, that´s good.
The game was boring (soporific 1st half) and Argentina deserved a bit more than Brazil (they could have win at the end with a Messi shot). When, at the end of the match, Ruiz whistled for the last time, Brazilian fans were shouting against their own coach, Dunga.