In assessing Frenkie de Jong and Matthijs de Ligt, few experts speak with greater authority than Ronald de Boer.

For a start, the Ajax and Netherlands legend has plenty in common with the pair. He, too, was at the heart of an exciting generation of youngsters that took the UEFA Champions League by storm and revitalised a flagging Dutch national team. And De Boer, like De Jong, was rewarded for those efforts with a big transfer to Barcelona.

But while shared experiences can help him relate, De Boer’s unique perspective on the duo – both nominated for The Best FIFA Men’s Player award - has been shaped by directly overseeing and participating in their development.

In his role as assistant coach with Ajax A1 – the top tier of the club’s famed academy – he witnessed first-hand their rapid rise through the ranks to global stardom and money-spinning moves. And while talent is never in short supply in the Amsterdam giants’ youth set-up, De Ligt and De Jong, it seems, always stood out.

“There was always something special about Matthijs and Frenkie,” De Boer told FIFA.com. “With Matthijs, you could see even at 17, when he was already playing in the second team, how mature he was.

“As for Frenkie, he was part of a midfield in Ajax’s second team with Donny van de Beek and Abdelhak Nouri. People would come to watch that team just to see that midfield play. You actually had people at that stage saying they enjoyed watching the second team more than the first team! The level of creativity was just incredible, and Frenkie of course was at the heart of it.

“Technique is always important at Ajax. It’s a given that we expect it to be of the highest level with all of our players - defenders included. Both De Ligt and De Jong have that, and they have other qualities which that set them apart as Ajax players: good vision, able to play with both feet, intelligent and always looking to take the initiative - not just being reactive. That’s what they have in common, and it makes them special.”

All the same, and while a long-standing, fully-fledged member of their fan club, De Boer did not anticipate De Ligt and De Jong – 19 and 21 respectively last season - emerging as stars of the Champions League and UEFA Nations League.

“Was I surprised by just how good they were? Honestly, yes. But I think the boys surprised even themselves,” he said.

“I had high hopes for them because it was obvious that they had real talent, and the right mentality too. But could anyone have imagined that they would do what they did for Ajax in the Champions League, or for the national team, so soon? To me, it would have seemed too much to expect.”

As it was, of course, De Boer watched the pair grow in stature – “they just got better and better” - as the season progressed. Seeing their self-confidence soar with every major test they passed took him back to the days when he – along with brother Frank, Patrick Kluivert, Edgar Davids, Clarence Seedorf and others – shocked world football by winning the Champions League.

“We only had a couple of experienced players back in 95 – Frank Rijkaard and Danny Blind – and every time we came up against a big team, we would think, ‘Wow, what a great opponent’,” he recalled. “Then we would play them, beat them and come away from it thinking, ‘Well, they’re great, but maybe we’re even better’. I saw that belief coming in De Ligt, De Jong and the others last season, and it was fantastic to see.”

As it became evident that Ajax's young standard-bearers were being sought by Europe’s top clubs, and that their departure was inevitable, De Boer also took a keen interest in their next destinations. He went public on his desire to see them follow his lead by swapping Amsterdam for Barcelona, citing a similarity in playing style that would make the transition less problematic.

But while De Jong heeded that advice, De Ligt chose instead to move to Juventus – and started last weekend’s Serie A opener on the bench. So, does De Boer fear that the young centre-back’s fledgling career could falter in Turin?

“Not at all - I have no worries about De Ligt,” De Boer responded immediately. “For me, he’s a player who can play in any team and in any system. He’s still young and he’ll make mistakes, but he has so many qualities. Even if he starts a little slowly - and it was the same at Ajax in his first few months - he will be a great signing for Juve. You can bet on it.”

Given the certainty and authority with which De Boer speaks, that would seem a safe wager. For now, the football world will follow De Ligt and De Jong’s development with the same excitement that once preceded Kluivert, Seedorf and the De Boers.