Reason: Is All Blacks aura of invincibility gone?
This weekend's match against Australia is not all about the world record winning streak.
It is not all about the Rugby Championship or the Bledisloe Cup.
No, it is about something much more precious to the All Blacks than any of that.
It is about their aura.
One of the great strengths of the All Blacks, perhaps their greatest strength, and that is saying something, is the fear they put into the opposition.
There is this image of invincibility.
There is the idea, nurtured for over a century, that the All Blacks always find a way to win.
It can be beautiful, it can be nefarious, but it is irresistible.
Of course, some countries have every reason to view the All Blacks as invincible.
Ireland still haven't beaten them in 100 years of trying.
Scotland and Argentina have managed three draws between them.
Wales haven't beaten New Zealand for more than 60 years.
It is a phenomenal record of success.
But as the All Blacks journey on through their unbeaten march of supremacy, one or two minor cracks have been appearing at the edges of New Zealand rugby.
They are not major fault lines, not yet.
But they are the sort of things that give the rest of the world heart.
After four consecutive victories at the Junior World Cup, the Baby Blacks have lost the previous three tournaments, one of them at home.
They didn't even make the final on two of those occasions.
Sam Whitelock, Aaron Cruden, Julian Savea and Brodie Retallick all came from the previous teams of winning Baby Blacks, along with six other players busting to make their way into the current first team.
But the next wave doesn't look so formidable, not unless you're South African or English.
The Black Ferns just lost to Ireland at the Women's World Cup, the first time they have lost a pool game since 1991.
It didn't get too much coverage in New Zealand.
It is best to airbrush these things out of history.
It's been a pretty dire few weeks.
The Crusaders lost in the final of the Super 15, a competition that only the Chiefs have won for New Zealand since 2008. And, after four consecutive victories at the Commonwealth Games, New Zealand lost in the 2014 final to South Africa. Not only did they lose, but they scraped past Scotland earlier in the comp and made some huge mental blunders in the final.
They came home sucking lemons, having seriously tarnished New Zealand's reputation.
Alasdair Reid, a fair-minded man, wrote: "New Zealand brought an unbeaten record that stretched back 16 years and encompassed four gold medals at previous Games, but they also brought a bad attitude and some pretty cynical procedures. Nobody wants powder-puff rugby, but their harshness went too far. Against Scotland they had two players yellow-carded for professional fouls, then made things worse by putting one of them back on before he had served his time in the sinbin. It probably had no effect on the result, but it spoke volumes about the unlovely culture of their side. Against them the Springboks put up the magnificent Cecil Afrika, a player with joy in every stride."
Gordon Tietjens' men were a let-down.
They were cynical at times.
They made stupid mental errors.
They lost composure in the big moments.
And when they lost, they looked like they were sucking on lemons.
It was a sight that gave the rest of the world strength.
For all these reasons, McCaw's men need to play like only they can at the weekend.
Again the world will be watching.
They saw a virtual England "B" team run New Zealand close.
They see Richie slowing, Carter crocked again, Tony Woodcock holding his back and the terrible worries about Kieran Read's recent history of concussion.
And they start to wonder as we swing towards World Cup year.
Are the All Blacks losing it?
It happens to even the greatest.
Just look at Tiger Woods.
The great golfer couldn't beat five club pros at last week's PGA Championship.
He clutched his back, complained of stiffness and said he couldn't get through the ball.
Phil Mickelson said, "I didn't really notice that. I just noticed that really on the greens the ball wasn't going in the hole."
"Ooh, cut," as my son would say.
Tiger used to own Mickelson when they were paired together.
He took pleasure in crushing him, and Mickelson was clearly intimidated.
Then two things happened.
Woods began to decline and Mickelson began working with Butch Harmon.
Tiger's old coach helped Mickelson snap Tiger's mind control.
A similar thing happened when Ireland played the All Blacks last year.
Joe Schmidt, Ireland's New Zealand coach, pulled away the Superman cape.
Ireland suddenly thought they could outmuscle, and even outplay, the All Blacks.
They did both of those things.
But it is one thing to know that the All Blacks are beatable, quite another to be convinced of your own ability to beat them.
It took Rory McIlroy a while to walk that walk.
But now the 25-year-old is moving like a champion.
The new Tiger, they are calling him.
Given the venues of next year's majors, I certainly wouldn't bet against McIlroy adding another couple.
The All Blacks have spent more than a century making the rest of the world believe in their superiority, just as Tiger fostered the belief that he was the chosen one.
England's prop Joe Marler called it "this All Black myth or aura about how they are invincible".
It is why they will be desperate to beat the Aussies on Saturday.
Not just for the record, but to restore the rightful order of things.