He returned to New Zealand in 2009 to become player-coach with Counties Manukau, building up his reputation until he replaced Sir John Kirwan as coach of the Blues.
That assignment has defeated many good men - Kirwan, Pat Lam and David Nucifora among them.
It's a bold move from the Blues - MacDonald is another virgin head coach - but Alama Ieremia has shown what can be done in a single season with his Mitre 10 Cup-winning Auckland team.
However, Umaga's courage and humility shone through. He fronted the media, talking about the switch in coach and sounding not at all like someone toeing the party line.
The modern way is to cut and run, issuing bland inanities - the press release, the sentence about respecting the person's privacy, and the oft-used line of "pursuing other opportunities" or "spending more time with the family". It's BS of the most nitrate-leaching quality; it fools no one and is code for defeat.
"I haven't admitted defeat," Umaga said in one interview. "I wanted to fight to be a part of it again because I have the utmost belief in this group of players and in the way this club is going forward.
"It was tough on the ego. But this wasn't about me. I've been fortunate to be part of teams where your ego has got to be checked at the door, and to get success, sometimes it's not about you. You've just got to go back to past experiences."
I can't claim to know Umaga well but I reckon I know what makes him tick - inherent in that first quote above. He wanted to fight to be a part of it again.
This is not a man who sidesteps a challenge just because it hasn't worked out. Facing people and making the best of things not only takes courage and parking of pride, it means the team ethic is still alive and well in him. He showed his team that he, too, could take being dropped, and that being demoted does not always mean diminished.
You get the distinct feeling that, while the stress of the Blues job got to him, he is a man who sleeps well enough because he has a strong grip on the practical realities of life - the joy and stabilising influence of family, a successful playing career, respect and recognition.
I recall him responding crisply at a press conference when someone asked him, as All Blacks captain, whether the weight of fans' expectations was too heavy. "No," he said. "It helps us win."
He likes winning, does Tana Umaga, and if winning means he has to accept a lesser role, he will do that.
Before he left for Toulon in 2007, I travelled to Wellington to write a piece on his last Hurricanes' training run, ironically held at his old Wainuiomata school. We sat outside the changing rooms, verbally travelling far and wide, when a woman interrupted. Umaga knew her, probably a parent or attached to the school, maybe an old teacher; Umaga addressed her with respect.
He didn't think twice about leaving the interview. Media are work, this woman was kind of family. They spoke at quite some length, seemingly about matters and people both had been involved with.
He came back to the interview with a gentle apology and it struck me that for most players, and particularly the All Blacks skipper, a smile and a wave to the woman would have sufficed.
He was bigger than that. She was a part of his wider team; the team who had supported him in life. He made time, maybe as she had given hers to him at another time. As she moved off, there was a spring in her step. Umaga had paid his respects.
It was a gesture from him but you could see she took it as far more.
A measure of the man.
