The world champions needed two late tries for wingers Julian Savea and Cory Jane to seal the 21-5 victory, and third successive win in the southern hemisphere competition, but the brutal defence of the Pumas and error-ridden All Blacks display were the main talking points from the match.
The All Blacks have attempted to play the game at a higher tempo than ever before this season, with the Pumas forwards appearing to be struggling to keep up with the pace of the game.
Their veteran players like try-scoring prop Rodrigo Roncero and captain Juan Martin Fernandez Lobbe, however, took the sting out that plan by meandering to set pieces and organising a brutal defensive screen around the fringes and in the backline.
"They're probably one of the best defensive teams in the world," Hansen said.
"The system they use is very good. They give you a lot of space on the outside and make you think there's a fool's gold out there and if you go too early with missed passes they drift out and cover that.
"And their one on one tackling is good. They're a very passionate team and have a lot of desire to play for their nation."
McCaw also pointed to the aggressive defence from their forwards, while the Pumas also slowed down the All Blacks' ball by flooding the breakdown, and proving virtually immovable when the home side tried to drive them off the ball.
"Around the fringes where we tried to get some go forward they defended that pretty well, slowed the ball down and we turned it over," McCaw said.
"I think that was what happened in the first half they had a lot of intensity and we weren't as secure as we would've liked."
The All Blacks committed numerous errors in the first half, forcing the pass, dropping the ball or turning it over.
Hansen put some of the blame for the high error count down to the gale force winds and driving rain that swept across the ground and blighted much of the first 40 minutes as a spectacle.
He did, however, also suggest their attacking mindset had been partly to blame, but once the All Blacks settled down in the second half they took control of the game.
"Our first half we tried to play way too much rugby for the conditions," Hansen said.
"We tried to move the ball at times when we should have held on to it. Our ball security wasn't that great.
"The second half we executed pretty good. Our ball security was a lot better. We ran better lines, were more effective at putting pressure on the Argentinians and were perhaps a little bit unlucky not to score another couple of tries.
"(But) I thought for the last 30 minutes of the game we totally controlled it and played in the right half."