Roger Tuivasa-Sheck and Rieko Ioane are the only two much-hyped youngsters to deliver what everyone promised on their behalf once they reached the adult ranks.
These two managed to find a way to stay grounded and focused and not believe they had made it because all those around them said they had.
They were the real deal - equipped with the sorts of skill sets that are built for the long term which is why the Tuivasa-Sheck is now captain of the Warriors at just 23 years of age and Ioane won two All Blacks caps last year when he was only 19.
But for every Tuivasa-Sheck and Ioane there have been maybe five others who have been equally hyped and haven't come to much.
The most recent example was Taniela Tupou, the so-called Tongan Thor who lit up social media in 2015 with his try-scoring exploits at Sacred Heart College.
Tupou was the biggest news ticket for a period that year. A 17-year-old, 125kg prop who could run like a back was a rare beast indeed and it was easy to see why Tupou had so many causal observers excited.
The thing was Tupou, though, was that those who had a more detailed look at his game could see there were multiple faults. His scrummaging technique wasn't great. His work rate was average and his ability to clear rucks wasn't all it should have been.
A lot of his game was fixable but there were plenty of other young prospects around who were further ahead which is why the Blues had a good look and passed him in, as did the other New Zealand Super Rugby teams.
The Queensland Reds, not so well endowed in the talent stakes or maybe not so discerning, snapped him up and here we are, still waiting for this kid to remind us why he set the internet alight two years ago.
The gap between schoolboy rugby and professional rugby is enormous and it is a path that only the most resilient can cross.
Talent may make for a great video montage and a world of clicks and views, but it is little or no guarantee of cracking the big time.
The qualities that actually sustain a top flight career don't make such great social media content, because graft, commitment and accurate decision-making can't be neatly packaged in a Facebook post.
It is difficult to portray the essence of work rate, dedication, discipline and single-mindedness in sound bite format.
None of this is to say that Nanai won't progress or deliver on his obvious potential. It is to strike a cautionary tone to lower the expectation and understand more fully that so many players who push on to the highest reaches are not the ones who obviously looked destined to do so when they were younger.
