The All Blacks coaches were right to come home from Europe last year concerned that their props had fallen behind the best in the Northern Hemisphere.
The coaches first suspected the rest of the world was catching up when the British Lions were out here in 2017.
Even in a series that had so much going on, the mobility and ball-running brilliance of Irish tight-head Tadhg Furlong stood out.
No one could put him down first attempt and in the second test, in particular, he damaged the All Blacks.
This wouldn't have been such a big deal had it not been for the fact that he was also rock solid in the set-piece – an immovable object one minute, an irresistible force the next.
He was the best, but by no means only prop in the Lions tour party who impressed away from the set-piece.
England's Kyle Sinkler looked a bit young and raw when he scrummaged on that tour, but young and exciting when he ran with the ball.
Mako Vunipola, when he wasn't flirting with getting himself sent off, had his moments of magic.
On last year's tour to Europe, there was further evidence that the Irish especially have upped their game in the front row and have a legion of mobile props who do all the nasty stuff and then run around with damaging impact.
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Cian Healy had a whopper of a test in Dublin and was replaced by Jack McGrath who was just about as good.
The Irish got 80 minutes of relentless carnage from their props while the All Blacks got all the set-piece foundation they needed from theirs, but not enough else.
The pendulum might have swung a little too far. The All Blacks, forever wary about being exposed at the set-piece, have developed a wide group of props who are all first-rate scrummagers.
When was the last time the All Blacks scrum was under any kind of pressure?
But it seems like in building this scrummaging power, the All Blacks have lost something in the open field. Their big men are not contributing enough elsewhere.
Specifically, the All Blacks coaches feel like too many of their props have fallen into bad habits – they stay on the ground for too long, don't have the urgency to get on their feet and back into the game.
They aren't working quite hard enough to get to the ball, get their hands on it and use a bit of footwork to eke out the extra metre in the tight which so often makes a big difference.
It's a fair concern as when was the last time one of New Zealand's props really made everyone go 'wow' with the contribution they made with their running game?
Karl Tu'inukuafe was a revelation last year but it was his scrummaging that had everyone in awe.
As All Blacks coach Steve Hansen said a couple of times, Tu'inukuafe was guilty of occasionally playing as if he was still 175kg in the sense that he wasn't backing himself to be more involved.
Much the same could be said of Nepo Laulala who is a solid beast but can often play 55 minutes without being noticed while even Joe Moody and Owen Franks, who are both world class in all aspects of their game, haven't shown up much away from the scrum in the last year or so.
The All Blacks coaches want to see the wow factor return to their front-rowers. They need more out of them – for Moody to provide more moments like the one he produced in the 2015 World Cup quarter-final when he off-loaded brilliantly to set up Tawera Kerr-Barlow.
They want to see Franks rekindle his passion for hitting short passes and breaking the defence. They want to see Tu'inukuafe, a natural ball-player, take responsibility for proving that.
New Zealand has regressed in an area where they used to lead the world.
For most of the last decade, probably two, New Zealand was maybe the only country that had dynamic, ball-handling, mobile props who were as much about pass-catch-tackle as they were crash-bang-wallop.
Tony Woodcock in his prime had a surprising turn of pace and wasn't afraid to find himself out in the open. And while he was a fully paid-up member of the front row in the sense he knew his core role was to scrummage, he didn't mind scoring tries.
Charlie Faumuina was a No 10 trapped in a prop's body and was such a vital element in the 2015 World Cup campaign.
He'd come off the bench and be a big contributor in generating width and continuity.
Even Ben Franks was ahead of many of the current props in his ability to contribute to the attack and the All Blacks want that edge back.
They want all 15 players on the field to be dangerous with the ball and capable of using it.