Playing at openside flanker and constantly riding the line around offside means test loose forwards like McCaw tend to draw the attention of whistle-blowers. But even Australian first-five Quade Cooper has more yellow cards than McCaw: four from just 57 tests.
All Black coach Steve Hansen was unimpressed with the booing of McCaw by fans at Wembley when he was marched off and again after the game during sideline television interviews.
Conrad Smith: I said sorry to the team
"It's normal over here," said Hansen, suggesting the fans' reaction had been out of order.
"We take it for what it is: a mark of respect against a great player. If you're no good, nobody cares."
McCaw stuck out a leg when lying in a ruck as Juan Martin Fernandez Lobbe tapped a quick penalty after 30 minutes, leaving Barnes little option but to send McCaw to the bin - to the delight of the large contingent of Argentina supporters among the record crowd of nearly 90,000.
Making matters worse for the defending champions, who pulled away for a hard-fought 26-16 victory, midfielder Conrad Smith joined McCaw in the bin in the 37th minute.
Asked about the booing and jeering, McCaw said: "I was sitting in the sin bin at the time so I didn't have much of a comeback after that ... [it was] a dumb mistake I made."
He added: "I knew straight away that it was a reflex thing and it wasn't the right thing to do. It put the team under pressure which you can't afford to do.
"It was one of those things that as soon as it happens you wish it hadn't."
Of the booing, McCaw said: "It's happened before and if you get wound up about it or worried about it it's not going to help you."
Smith's yellow card - for interfering at a ruck in front of his posts - was less clear cut, but Hansen said afterwards that both cards were fully justified, adding that they contributed to a difficult afternoon against a fired-up Pumas defence.
"The fact that we gave away two yellow cards which were both warranted meant we played 20 minutes with only 14 players," Hansen said.
"That's what makes it a bit tougher. In saying that, I'm happy with our guys. We showed a lot of fortitude.
"We haven't played for five weeks so the game will do us the world of good."
The second-half introduction of Sonny Bill Williams, Beauden Barrett and Charlie Faumuina asked a lot more questions of the Pumas and in the end they were the key to the All Blacks' success.
Williams in particular was outstanding - charging at the line and playing with an energy that was at a different level from that shown by his teammates.
