Brazil knew the weak spots - Argentina's left defence - and exploited it with speedy attacks and precision feeding of their strikers. What helped them a bit was Messi falling back to midfield after being repeatedly tackled aggresively (not necessarily with fouls). And all teams are well aware what Brazilians do when in flow.
The Argentininas were definitely not less muscular or weaker than Brazilians. But the Argentina dint have to sacrifice flair to beat Brazil. They lacked ideas when dealing with Brazil. They lost the mental game, so when their rhythm was checked they just wilted.
