All Blacks coach Steve Hansen didn't quite get around to saying late last year that he's trying to build two back three combinations, but hinted at it. Reading between the lines, he wants one back three combination that is set-up as a kick-catch unit and another that has more strike power and ability to test defences with their running and finishing threat.
Having that versatility will be imperative because they may want to select different options for specific opponents and even have the ability to change the set-up during games.
As a rough example, they may want a kick-chase back three to play South Africa in the opening game but possibly a counter-attack back three with more running power should they meet Australia somewhere along the way.
Ioane and Smith feature in both versions and the kick-chase unit probably had McKenzie at fullback.
But that's gone now and it is not apparent how the coaches may reshape their back three in either of the two options.
Getting this right is going to be crucial in Japan.
At the last two World Cups in England and at home, the All Blacks got their back three spot on.
In 2011, they made a selection masterstroke with their back three. They correctly predicted that it would be a kick-chase World Cup: that most sides would use the attacking bomb as their first and preferred means of using the ball.
The weather in New Zealand at that time of year was going to be unsettled, probably wet and probably windy. To win the World Cup, the All Blacks felt they needed a back three whose core strength was accuracy and bravery under the high ball. That was the bit each individual had to get right first and their ball in hand, running game was the secondary consideration.
The All Blacks, in elevating Israel Dagg to fullback ahead of Mils Muliaina and being so patient with Cory Jane, who was out of form throughout Super Rugby only to find his confidence in July, had two of the best back three players in the tournament.
Their decision to ask centre Richard Kahui to play on the wing was the final act of genius as he was superb. He was defensively rock solid and caught everything that came his way, while offering the All Blacks a genuine finishing threat.
In 2015, the balance shifted in terms of skill sets and combination. The view for that tournament was that the All Blacks would need two all-round footballers and one power wing. The rugby in England was more open, more creative and as a result there were more attacking opportunities with ball in hand.
The combination of Smith at fullback and Nehe Milner-Skudder and Julian Savea on the wings gave the All Blacks the ability to score tries through ground strikes.
It also providing them with enough composure, accuracy and skill in the aerial chores to be comfortable they weren't vulnerable to a kicking onslaught from the opposition.
So what McKenzie's injury may have done is simplify the thinking and persuaded the All Blacks that to create two distinct back threes, they just need to change their right wing — depending on what they are trying to achieve.
With Milner-Skudder a non-starter because of injury and Dagg retired, their options are fewer than they might have been.
It would now seem that the best way to set up both back three options is to have Smith locked in at fullback and Ioane on the left wing.
To build a kick-chase option, the selection choice would appear to be a straight head-to-head between Jordie Barrett, George Bridge and David Havili.
All three are comfortable at fullback. All are good at getting off the ground to meet the ball and all are capable of kicking long to relieve pressure.
And it they want finishing power, then it will be a case of hoping Waisake Naholo comes good at some stage between now and September because there is no other power runner staking a claim.
Ben Lam has his moments but somehow doesn't quite look ready for test football and that's about it in terms of genuine possibilities.
