Dictatorial and task-focused when he went to Wales, Henry's nadir was the Lions in 2001 when he didn't so much lose the changing room as never have it. He evolved in 2004 when he had his epiphany in Johannesburg; his All Blacks wilted in their final Tri Nations test and Henry could see the team culture needed a revolution.
Since then the All Blacks have become the world's most player-driven team. They have a culture of empowerment and responsibility that goes beyond anything their rivals have. The strength of that culture was key in persuading Dan Carter and Richie McCaw to stay; it has been instrumental in not only persuading Ma'a Nonu to stay but in bringing out his best after a torrid campaign with the Hurricanes and it has been an under-estimated factor behind the success enjoyed since late 2004.
Henry's tenure should be bullet-proof; his legacy as the best coach of the professional era already locked in. But such is the cruelty of a coach's lot that everything could be forgotten in the next few weeks. The pyramid Henry has erected could be dust by as early as this weekend; maybe the next or it could be in the final that his world caves in.
Henry can outscore the likes of Woodward, White and MacQueen on all fronts bar one; and it is the bar one that matters most. The fact Woodward picked up a knighthood for coaching England to the 2003 World Cup says it all.
Like it or not, the World Cup has become all-consuming in rugby. How many New Zealanders have taken centre stage in a London bar during a Tri Nations victory only to have their bubble burst by a World Cup barb? Without a modern World Cup title, the jigsaw is incomplete.
A second World Cup failure will leave an indelible stain on Henry's record. No one will see past a double failure as his re-appointment in 2007 was about redemption; he was the first All Black coach to survive a bombed World Cup campaign and the vitriol that spewed out of the nation four years ago will erupt again should New Zealand not secure the title this time.
Henry has acknowledged as much. "At the end of the day the big one is the Rugby World Cup and everybody knows that, so that is going to define this team and the people associated with it."
It hardly seems fair but that's how it is and Henry has always given the impression he can live with it. There have been sardonic references to 2007 in the past four years. There have also been times when he's spoken with sincerity about that night in Cardiff four years ago and provided a window into the hurt it caused.
Failing at a World Cup leaves no room for ambiguity. Grand Slams and Tri Nations victories are not a lifeboat.
The legacy sinks the instant the whistle is blown and the scoreboard isn't showing the right balance.
All Blacks talked publicly in the build-up to the clash with Canada today about how Henry is not the same in private he occasionally appears to be in public. He's approachable and wry; he is, reckoned John Afoa: "Just another bloke. He has kids and grandkids he loves to talk about. When we are off the pitch everyone gets along and we just chat."
Ali Williams put it like this: "From the outside the perception is probably not the reality. He has a great sense of humour, he is a man that shoots straight at you and tells you what he wants and lets you know where you stand."
The respect in which the players hold Henry is obvious.
But Williams was wrong about one thing - perception is reality.
The reality for Henry is that his legacy needs a World Cup. Without one he'll never hold the place in history he deserves.
