There's little doubt about the magnitude of the job he faces with Moana Pasifika losing all their Super Rugby Pacific games this season finished - apart from one, the last game of the season.
At the end of the season, Aaron Mauger quit as head coach of the side after two difficult campaigns.
Umaga said it was the 'purpose' which drove him to accept the top job.
"What it means to a lot of people, what it means to a lot of players, the opportunities for our Pacific Island nations, the purpose was strong, and it drew me to it and made me put my name towards it," he explained from Samoa, where he is defence coach for Manu Samoa as they prepare for the Pacific Nations Cup.
As he acknowledged, being head coach will bring a lot more of stress.
"Oh yeah, you get a lot more sleep as an assistant coach, you just do your job and then go home," he quipped.
"I'm sure head coaches will tell you there's a lot that gets on your mind. The ability to manage up, sideways and down, that's something I learnt with Leon (McDonald). It just comes down to making sure everyone's informed about what's happening.
"There's a major difference, you're heading a programme, it's all on you, it's what everyone's looking at. And I think I'm old enough now to be able to deal with that. I've really learnt from my time being an assistant (at the Blues)."
So, after five years away from a head coaching role, he now returns with blessing of wife Rochelle and his family.