The inside word is that when it comes to explosive drills in the gym, he posts the best results and that while Rieko Ioane can be moderately confident he would win a foot race between the two of them, no one else in the All Blacks squad can be.
"Vaea is a really, really good athlete," says Hansen.
"Probably one of the best athletes I have had anything to do with from a natural, sheer ability point of view.
"He came into the squad and we have put six kilos on him which I think is remarkable from both him and [strength and conditioning coach] Nic Gill and the team. They have worked really hard in the gym and it is all power and strength.
"So we want to see a real physical beast which we know he can be but we also want to see him do his core roles. Dominate in the tackle, dominate when he carries, use his ball skills in the contact area as well.
"We are expecting a lot from him because we believe he has a lot in him. We are going to aim [high] with him and he needs to aim high as well and if we aim high I think he will hit the target."
It's that word dominate that will no doubt prick a few ears.
Many a good blindside athlete has gone before Fifita, rated highly for their gym work, speed testing and agility.
Not so many of them, however, have made the transition from great athlete to great player.
Not great test player anyway.
Athleticism is only part of the package. It is, as Hansen says, the ability to use that raw, explosive power to good effect that matters.
The opposition need to know that the bloke wearing the All Blacks No 6 jersey is not gym tough but match tough and that's the real reason there is such confidence in Fifita.
The coaches have seen him bring the necessary edge to his work with the Hurricanes this year.
They like the way Fifita throws himself into everything, that he's confrontational and aggressive both with and without the ball.
He's a different body shape - taller, leaner and more angular - to both the other sixes in the squad, Liam Squire and Kaino, but he makes his frame work for him.
Fifita has a high knee lift and long strides making him awkward for defenders to bring down.
"He's just about one of the fastest people we have got in the team," says Hansen.
"That's not bad for a six. He is physical and he likes being physical and that is not something you can coach, that is something that comes from inside you.
"That's a Jerome Kaino-type player, a Jerry Collins type, a Rodney So'oialo type of player.
"Chris Masoe liked and enjoyed being physical and that is quite handy to have someone in your team like that because it usually puts the fear of God in the opposition if they are good at it.
"And we are hoping he's going to be good at it."
All Blacks team to play Argentina in New Plymouth on Saturday:
Damian McKenzie, Israel Dagg, Anton Lienert-Brown, Sonny Bill Williams, Nehe Milner-Skudder, Beauden Barrett, TJ Perenara, Kieran Read, Ardie Savea, Vaea Fifita, Brodie Retallick, Luke Romano, Nepo Laulala, Dane Coles, Joe Moody
Reserves: Codie Taylor, Wyatt Crockett, Ofa Tu'ungafasi, Scott Barrett, Sam Cane, Tawera Kerr-Barlow, Lima Sopoaga, Ngani Laumape
