Both currently look exceptional bargains, real stand-out players and have had immediate, significant game time. Add to that the incorporation of the excellent, wily Miralem Pjanić, the promotion from Barça B of Ronald Araújo – who’ll save them millions on buying a centre-back – and the emergence of record-shattering Ansu Fati, just turned 18.

Then there’s Sergiño Dest, another superior tyro-talent. It’s worth stopping here and turning the focus back on Koeman. Even before his impact was felt, or a ball had been kicked competitively, he insisted on signing the Dutch-born USA right-back from Ajax. It was fully his initiative and the football department had to abandon plans to add Max Aarons from Norwich.

For the first few games, 20-year-old Dest was required to adapt and play off his weaker foot at left-back. Not only did he shine, it was fascinating to witness a reversal of the dominant theme since Koeman got the job he’d coveted for so long. He stands for back to basics, order, common sense, players used with strategic intelligence in their best positions – a return to roots.

On the hoary subject of football people overcomplicating the world’s favourite sport, Barcelona’s coach has much to say. “Sometimes coaches will make things too difficult. This game is still just 11 v 11. You must have good organisation in a team. You need to assess the individual qualities of the players, like we have done with Messi.

“The others in this Barça team, they must do a lot of work – a lot of running, because then Messi can still be the best player in the world. And this applies to all our guys, every other position. But I don’t ask for qualities from a player which he does not have. With everyone in their position, playing to their strengths, this team will be stronger.”

As far as Koeman is concerned, that was never more obvious than during Bayern’s 8-2 dismantling in the Champions League quarter-finals. “For me, that was the big lesson. If you don’t play as a team, you will not win. To play against opponents like Bayern, a really strong team with a lot of individual qualities, you must have the best organisation.

“Look at Bayern’s physical state: it’s excellent, and their organisation was excellent. That was a big difference on that night against Barcelona. For sure, my players will have the intention to take revenge for what happened in Lisbon.”

Back to Dest. He’s clearly ambidextrous and, while more confident and dangerous in attack, his versatility is further evidence of how Koeman helped to facilitate Barcelona’s squad rebuilding. And his arrival came after seasons when significant outlay on Philippe Coutinho, Ousmane Dembélé and Antoine Griezmann provoked intense scrutiny.

But although Dest, Ansu and Pedri have already played in at least two positions, despite barely being through the doors, Koeman’s architectural mantra remains the same: square pegs for square holes, round pegs for round holes. That’s especially true of a player he advised to sign up for Blaugrana duty in 2019.

Frenkie De Jong, now pivote in a 4-2-3-1, takes up the tale: “He was really positive about Barcelona, the club and the city, when I called him about the move last summer. He just told me that I have to be careful, that I shouldn’t go to restaurants too much or eat too much because life is really good in Barcelona – sometimes you can feel like you’re on vacation the whole year.”

Koeman, now De Jong’s boss, returns serve. “Last season, Frenkie didn’t play in his best position, which is always difficult for a young player who comes to Barcelona. It’s already a big change – the language, how they live, how they train. Frenkie is a very clever football player. He sees all the situations on the pitch, takes the right decisions. The most important thing for me is to put him in the right position in Barça’s team. I will give him that support because there’s no question about his qualities. I feel the same about every player: Frenkie, Griezmann, Coutinho. Deploy them in their best position, then they can make the difference.”

Perhaps Koeman, himself, is finally a square peg in the slot specifically ‘meant’ for him. His best position. Barça coach. Be sure that whatever happens during his reign, however long it lasts, Koeman’s little clutch of starlets are working for a talented tutor.

Among those who can attest to that is Virgil van Dijk. The two were maestro and emerging behemoth together at Southampton from 2015 to 2016. Van Dijk, having now won the Champions League with Liverpool, told me that he felt picked upon, cajoled and unnecessarily singled out during many Southampton training sessions. Having emerged from the experience to vast success and acclaim, the Dutch centre-back also admitted that Koeman’s micro-coaching, however stern, had been central to his rise and rise.

“I like to be the same coach for every player,” responds Koeman. “But sometimes a player who has a personality and plays in the same position I played, you can give him more attention. It was great to work with Virgil, because he was an open guy in terms of communication. He liked to learn from everybody, and he had to change his personality a little because sometimes he was a bit too lazy. Maybe people will tell you he was a little bit arrogant in his football.

“On one side, it’s nice, but I always said to Virgil, ‘You have to know the other centre-back will make mistakes and what is your position then?’ If you think, ‘Oh, he will do it,’ you’re in the wrong position. You have to always know what your position should be if there’s a mistake. And then your position needs to be that position. We worked really hard but, finally, the credit is for Virgil because he is now, in my opinion, one of the best defenders in football.”

Now the lessons continue at the Camp Nou, where Pedri, Dest, Ansu, Dembélé, De Jong, Trincão and Araújo all look like the bedrock for a youth-inspired but old-school Barça revival. Whether or not that eventually transpires, there’s no question that their early development in Barça’s renaissance is in the hands of a proper football professor who’s back at his alma mater. And ready to teach.