Ireland's 23-12 win over New Zealand in the second Test on Saturday which has sent the three-match series to a decider was historic but not unexpected.
If there had been a canary in the gold mine, warning of the insidious forces behind the All Blacks' recent decline it has been Ireland. The Irish hadn't beaten New Zealand in 113 years until they did so for the first time in 2016.
They now have won four of the last seven Tests between the teams, at venues as diverse as Chicago, Dublin and Dunedin where they achieved their first-ever win over the All Blacks in New Zealand on Saturday.
All Blacks fans were shaken not just by the fact but the manner of Saturday's defeat. Ireland controlled the game from the start, keeping the All Blacks under pressure, forcing them into mistakes. At any point in the match, New Zealand was barely hanging on especially when reduced to 13 men twice during the first half, to 14 for all of the second spell.
Lack of discipline was the most obvious of many failings in the All Blacks' performance and they now head to Wellington for Saturday's deciding Test under unprecedented pressure. A confident Ireland team who, having achieved an historic test victory, now have set their sights on an even more momentous series win.
The ramifications of the All Blacks' loss have been immediate. When new world rankings are released this week, New Zealand is expected to drop to fourth place, matching its lowest-ever ranking.
To some degree the ranking may even be generous. The All Blacks recently have lost to England, South Africa, France and Ireland, suggesting that on disclosed form they are possibly only the fifth-best team in the world.
The social media reaction of New Zealand fans also was typically harsh: All Blacks fans seldom accept any defeat with equanimity.
Many fans called for the sacking of head coach Ian Foster whose popularity even before Saturday's match was low. Others called for captain Sam Cane to go. Fans separately called the All Blacks performance awful, painful, tragic, a shambles and a farce.
Foster, at his most somber during a post-game news conference, matched that mood and called the performance "unacceptable" and "sub-standard."
In the week leading up to the final Test, Foster said "we've just got to trust ourselves and trust what we do and ultimately back your own skill level. That's something we've got to go away and work hard on."
If New Zealand lose again next weekend, the odds that Foster will lead the All Blacks to next year's World Cup in France will shrink substantially.
The cause of the All Blacks' recent poor form is hard to define. Northern hemisphere teams unquestionably have improved, often under the guidance of New Zealand coaches who were unable to find positions in their own country.
England, Scotland, Wales and Ireland all won Tests against southern hemisphere opponents on Saturday to send their series to deciding matches.
One important factor is that the standard of Super Rugby - the southern hemisphere's main professional competition - has fallen, especially since South African teams quit the competition to play in the northern hemisphere. The tournament no longer serves its purpose of developing players of Test calibre.
At the same time, New Zealand Rugby has been distracted from the deterioration in the standard of the domestic game while pursuing a deal with the California-based tech investor Silver Lake which it regards as essential to ensure the financial health of rugby in New Zealand.
With Australia now poised to quit Super Rugby in 2024, a decisive move is needed to create a new competition which can underpin the strength of future All Blacks teams.
