Towering wing still work in progress
You can coach tackling, work-rate, high-ball technique. You can't coach speed, size and scare-factor.
Frank Halai is raw and gifted.
No-one will tell you he is the complete player; no-one will deny his lethal attacking ability, either.
Eight tries in his debut Super Rugby season emphasise that.
At the same height (1.95m) and only seven kilograms lighter (105kg) than the imposing Brad Thorn, Halai's potential to become an intimidating test wing is immense.
Imagine Thorn supercharged and running on rocket fuel.
That's what the All Blacks see in Halai; an unrefined man mountain with more upside than Mount Aoraki. He is a born finisher.
Sure, the Blues wing has progress to make; deficiencies on defence and nerves securing up-and-unders that could prove costly, if exposed on the international scene. Just last year there were similar concerns about Julian Savea.
On the field, look at where Savea is now. In time the same could be true of Sir John Kirwan's prodigy, too. After all, the legendary All Blacks wing knows a thing or two about quality No 14s.
"He's a really intelligent footballer who works hard. Couple that with his size and ability . . . and I still think he's got 40 per cent more to grow," Kirwan said.
"You're starting to see more determination and confidence.
"His all-round game keeps improving. He's young from a rugby point of view. He hasn't played a lot of football - that's important."
Kirwan's final point is, indeed, revealing. The contrast to Halai's fellow Blues' bolters is compelling.
Midfielder Francis Saili, outside back Charles Piutau and blindside flanker Steven Luatua are younger but much more advanced in their rugby education.
It's hard to believe Halai is, meanwhile, still finding his feet.
He has barely scratched the surface in the 15-man code. In three NPC seasons - two with Waikato before transferring to Counties Manukau - the 25-year-old played less than 10 games.
Until this year, Halai thought he was destined for a long career with Gordon Tietjens.
"To be honest I never thought I'd make the All Blacks, or the training squad. I thought I would play sevens all my life," Halai told Sunday News before last night's game against the Crusaders.
"I was lucky enough to get the chance to play some XVs and to get the news I'm in the All Blacks wider squad . . . I'm stoked."
With Richard Kahui's shoulder gone and Cory Jane still recovering, Halai will now be competing with Savea, Rene Ranger and Hosea Gear when Steve Hansen names his 30 or 31-man squad for three tests against France on June 2. Ben Smith is seen more as a fullback/centre.
Surprisingly, it is a hard task-master, rather than soft approach, that is behind Halai's sudden rise.
"If I do something wrong out on the field, he [Kirwan] will yell at me," Halai said. "It's a good learning skill."
That, it seems, has brought out his best. Speaking to the towering Tongan is not easy - like many Pacific Islanders he is shy by nature. Kirwan, however, has implored him to come out of his shell once he steps onto the field, and feels that is what he needs to evolve further.
"When you get across there, if you are going to be shy you're not going to be selected," Kirwan said.
"He needs to learn to communicate out there. I don't care how shy he is off the field, when he gets out there he has to do his job and he is learning."
At the first All Blacks camp in Mount Maunganui this weekend, Halai's next step begins.