Mental preparediness became key for the All Blacks ahead of the knock-out stages of the Rugby World Cup.

The All Blacks had to be careful their off-field friendships with South African players and coaches didn't undo their defence of the rugby world cup, a manager has revealed.

The All Blacks took more than a thousand hours of video and nearly a million pieces of match-data to Britain to help analyse the performance of their rivals.

But the data scientist charged with turning that data to the team's advantage, NZ Rugby performance analysis manager Jason Healy, played down its significance.

Instead, the secret to success lay within, and the team's focus turned increasingly inwards as the competition entered the knock-out stages, he said.

READ MORE: All Blacks data tech helps Massey University

Speaking at a conference in Wellington organised by NZ Rugby's analytics software supplier, United States firm SAS Institute, Healy said the eye-opener for him was that data analytics was about "more than just the numbers".

"No-one probably needed to be reminded about what happened in 2007," he said, referring to the All Blacks quarter-final defeat by France.

"We didn't talk about it, but we knew emotionally and mentally some of the guys were thinking about it.

"The really critical thing that came out of our summation of the pool play was that one of players came up to us and said 'no-one fears us, nobody is scared of us or intimidated by us'. That was a real lightbulb moment for us."

It was no coincidence French lock and "number one line-out taker" Yoann Maestri was crunch-tackled by Jerome Kaino early in the game, Healy suggested.

Dan Carter spotted the large Frenchman was slow to rise from the challenge and exploited the situation by kicking behind for a line-out, in a sequence of play that established the All Blacks' early dominance.

Conversely, the All Blacks had to make a deliberate effort to put their off-field camaraderie with the South African team out of their minds ahead of the semi-final, he said.

"Because South Africa are an amazing bunch of people and the players and coaching staff have a lot of friendships, we had to 'not go there' – to the emotional side of our thinking.

Parading the mindset that could otherwise have come into the All Blacks' game, Healy said: "I don't want to hit you because I like you. You can have it; I'll get the next one."

"We can't have that kind of thinking in this game. We had to be 'blue head'; cool, calm and collected.

"We knew we were going to have a beer with them after the game, even if World Rugby didn't necessarily think that was the best thing to be doing."

The All Blacks' information arsenal included videos of 275 games, each filmed from four angles and synchronised with 3500 hand-noted match "events", such as line-outs and missed tackles.

"If you want to see anything that happens in rugby, we can go back and show you a contextualised example with video."

SAS' software helped present that information in a fun and easy way, Healy said. That was key, given the All Blacks' 52-strong squad of players and managers ranged from 65 year-old managers who didn't use smartphones, to student players undertaking information technology degrees.

"Humans don't make decisions based on information, humans create 'ideas' from information and that is how our environment works; we need to be able to take them on a journey.

"In our All Black environment – and probably a lot of environments in sport – not everyone likes numbers."

However it was presented, data couldn't "see, hear or feel" and "these are pretty critical things in a rugby game", Healy said.

"Data doesn't hear the calls that are being made during the set piece, can't see the opportunities that the players see, and can't feel the intense pressure and pain that players feel.

The All Blacks "didn't have a hell of a lot of information" to help them prepare for their pool match games against Georgia, Namibia and Tonga, because they had played few recent tests, Healy said.

Conversely, with 650 test caps between them, the All Blacks' starting team for the final had a huge amount of experience. "You don't need to cloud that with information. You need to trust them.

"We made sure the information was available. They could go to the data if they wanted to; some of them wanted to look at line-out databases."

For example, one player used SAS' reports to review all seven-man line-outs taken by Australia when the Australians had chosen to drive, Healy said.

"[But] our systems are processes are that good that the execution and requirement for knowledge became less and less as the tournament went along. The players started to trust themselves more."

Healy emphasised the importance of the All Blacks' culture in its dominance.

"You are an All Black '24x7' and if you are past All Black, you are an All Black. They put themselves second and the team first. It's a pretty cool environment you don't want to leave."