There was a time in the Ajax academy when Matthijs de Ligt was making none of his youth team coaches happy. The 13-year-old De Ligt was already heading up towards 6ft and could put on muscle quite easily. As a centre-back in that age group, he was almost like a cheat code.

At De Toekomst, Ajax's impressive academy facility, they knew this was pointless for De Ligt's development. He was getting nothing out of it. So Ruben Jongkind, the former Ajax head of academy development, and academy chief Wim Jonk took the decision to take De Ligt out of his comfort zone.

No longer would he marshall the defence for his own age group, but he would step up a year or two. And he would start playing in central midfield. It was visionary for the individual's development, but it didn't go down well with everyone.

"We saw already that he had a let's say in the total footballer model that we used back then. We had a very good eye for the individual," Jongkind, who first watched De Ligt when he was 11, told the Manchester Evening News.

"It was also the Cruyff plan to educate the individuals, focus on that and shift the focus from result-driven youth academy towards long-term development plans for each individual. So we were analyzing him. Okay, he has good technique, he has a proper physique, he understands the game very well and his mindset is really good. He's a winner and also a team player. So people saw that he can become a great player.

"But then it was funny because the coaches wanted to keep him in their respective teams. So when he was U13 or U14 he was playing centre-back and of course, he had so much that it was hard for the opponents to score goals against him."

Jongkind and Jonk looked at what De Ligt would need to make it as a centre-back at Ajax. He would have to play a high defensive line, he will need quick reactions, he will almost be more of a midfielder than a defender.

They felt he had to work on his agility and speed to get back when that high line was breached, to be quick enough and light enough on your feet to cover that space. It is the full package that has interested Manchester United in signing the now 24-year-old this summer.

"That's why he should be moved up to the midfield and he should be playing in one or two teams higher because now the challenge is not there for him," said Jongkind.

"That fight, we had to change the culture and then focus on him and his development. That's one thing that we did in terms of the matches that he played, in terms of the training, the same thing. So we moved him up in training to much older ages."

Jongkind believes the decision to challenge the youngster both positionally and in terms of his age group paid dividends. Had he stayed with his own team, he would never have been playing a Europa League final at 17.

That match, in Stockholm against Jose Mourinho's United, meant De Ligt became the youngest ever play to start in a major European club final. His ascent looked unstoppable.

That was only because of the work that had gone into his development. From the moment Jongkind first watched him play he knew there was a naturally talented football there, he just needed bits adding.

Ajax set up physical coaching sessions with former 800m European champion Bram Som, who worked with De Ligt on his agility and running. Coupled with playing in midfield, his coaches started to glimpse that development into a player of first-team potential, adding technical skills to his natural game intelligence.

"Because he played up a lot in the midfield and he also understands the game, he understands what he needs to be able to do in technical terms," said Jongkind.

"The first touch, where does it go? I need to go forward. I have to think forward, what does it mean for my positioning? What does it mean to direct my teammates in a way that we can play forward quickly, to get superiority in the midfield. Already at a young age because he's also a bright student in academic terms."

With De Ligt, those in charge at Ajax's vaunted academy were always thinking two or three years down the line. It was about challenging him and putting him in situations that would aid his development and make him a player capable of representing the first team. It wasn't just within the academy itself that they had to battle to achieve this.

"I also remember a case where I think it was the under-16 or under-17 national team," said Jongkind. "They wanted to play him in some kind of friendly tournament against Albania and Wales, and we wanted to take him as a 15-year-old to the UEFA Youth League. I think it was quarter-finals or semi-finals, it was a big game for the under-19s.

"This was a big, big issue because the federation, they wanted to take him to these matches, where he would play his own age group against Albania. It's nothing for him.

"In academies and federations, back then at least, you had this urge to have the best player to win those matches. But nobody gives a damn if Matthijs wins or loses against Albania.

"But playing, let's say, a top match three years older against Barcelona in the Youth League, it's a completely different test. That was to prepare him for first-team football, the pressure and everything."

After three years in Serie A, he moved to Bayern Munich for EUR67m. Two years on, they are prepared to sell him at a loss to United. Jongkind insists the last five years haven't been as bad as some claim, but stresses now is the time for his former protege to step out of the shadows and become the main man somewhere.

"The average age in Serie A is 28, 29. When you play Ajax as a youth player, it's one thing, you know, there's no pressure, you can make a mistake and everything. When you go up in a higher level, then it's every week, you have to be there," he said.

"I think he is very capable of dealing with pressure, but you also need the experience and his time will come. Sometimes you need to give those players a break, if you expect them to perform from 17 and play all the time at the highest level, I don't think it's always realistic for all players. I think his development is pretty good, he played a lot of matches for Juve, a lot in the Dutch team. He's still only 24.

"But now it's the time to really become like a pillar in the team and not be like, let's say the first 14, 15 players, but really become a crucial player."

That could happen with a reunion under Ten Hag and Jongkind believes a rekindling of that relationship could be beneficial, turning a potential EUR50m deal into a bargain for United.

"I think so, he was catapulted straight from the academy into the first team [at Ajax] which was very easy for him back then. I think Ten Hag told him new things and details for the top and I think Matthijs could be of great value for United," he said.