‘Fundamental,” Zinedine Zidane said. Karim Benzema had scored, Cristiano Ronaldo had scored, and Gareth Bale had provided the assist that led to Barcelona’s defeat in the clásico, turning the season upside down, but Real Madrid’s manager was not talking about the BBC triumvirate. He was not talking about Toni Kroos, provider of the other assist, or about Keylor Navas, his habitual saviour, either. Instead, his mind was on the man in the middle: Carlos Henrique Casemiro.

In the post-match photo, Madrid’s players are celebrating, clenching fists and shouting, in various states of undress. Casemiro stands but does not stand out; still in his kit, he is half‑hidden behind the rippling torso of Ronaldo, almost like a comment on the way he plays. You might not notice him on the pitch, but you notice when he is not. That night Madrid won 2-1; five months earlier they had lost 4-0. There were two differences in the starting XI, Casemiro was one of them.

Things have changed for him since then; and things have changed for Madrid, too. “I feel respected as a player now,” Casemiro says. The odd thing about that is that the manager who did not play him, Rafael Benítez, was such a firm, clear believer in his importance that when he took over at Real Madrid, Porto swiftly exercised their option to buy on Casemiro, enabling them to charge the Spanish club more for exercising the buy-back option of their own – so sure were they that Benítez would want him.

But wanting him was one thing, playing him was another. Casemiro played a key role as the season developed, a regular starter in the weeks leading up to the clásico but when the game against Barcelona came around, the manager listened to “suggestions” as to who he should start. This was the most galáctico and least Benítez of teams. James Rodríguez and Isco started, Casemiro did not, Madrid lost 4-0.

The Brazilian’s absence alone does not explain the heaviness of the defeat, but it does help. Analysing the game, Alberto Toril, his former coach at Real Madrid’s B team Castilla, said: “Madrid missed someone like Casemiro in the clásico.” Privately, Benítez agreed; his successor, Zidane would too when he took over in January.

If Zidane’s support for Casemiro surprised, it should not have done. Casemiro may not be one of the president’s men but luckily for him the president does not pick the team. Not right now, at least. Among the most important regrets that Benítez will have from his time in charge of Real Madrid is listening to those “suggestions”, leaving out the man who provided him with the thing he treasures most of all: balance. It was not a regret that Zidane wished to repeat. And he had the authority and prestige to pick his own team.

Zidane may have been the most elegant footballer of his generation, but he preferred to see himself as a competitor and was alert to the importance of the role played by those around him, men who provide balance and protection. Men without whom things came crashing down. Zidane knew: he had seen it. Despite all the galácticos, or perhaps because of them, he had retired from Madrid after three trophyless seasons – that drought was part of the reason why he left when he did, in fact – and his diagnosis was clear. Talent alone does not make a team.

A year before, Zidane had returned to the French national team on one condition: that Claude Makélélé returned with him. And, looking back on Madrid’s collapse a decade later, he admitted: “When he left we missed Makélélé. He was the only one who always, always, kept his position. He never went. Never. He knew what he was doing, and he was the reference point for the team.” Casemiro, Zidane recognised, was similarly “fundamental” – a player in whom Nilton Moreira saw “a Dunga or a Mauro Silva”.

Moreira first met Casemiro when he was six. Casemiro’s cousin played for the girls’ team at the soccer school Moreira ran in Sao José dos Campos and recommended him. He would stay there until he was 13, before heading to São Paulo, where he was running the midfield at 18 before his €5.2m move to Castilla, Real’s B team but finding a place in the first team was not so easy. Others stood before him, and at boardroom level there was little appreciation for what be brings. He sat out too often and when his spell at Porto ended, brought back by Benítez, the same happened again in the biggest game of the season.

Now, at last, he is recognised as a necessity. It helps that there is no one else. “Casemiro is a positional midfielder ... and the only one they have,” Toril said. There is something eloquent in those words; even with his limitations, Casemiro is essential, not least because this squad has limitations, too. He may not be perfect, but at least he is there: diligent and disciplined. No one else can fulfil his role and no one else really wants to, either. Toni Kroos started well enough in a deep midfield position but eventually disengaged. Casemiro does not. Only he will do that job; as one coach puts it: “He actually enjoys it.”

He does the dirty work. Quite literally: no Madrid player has committed more fouls in La Liga this season. “He fulfils the role that an offensive team needs, giving balance,” Benítez said of him. “He fights for the ball and helps the central defenders. If the team attacks and exposes itself, it needs a player like Casemiro; he helps to sustain the system.” The system, not himself. He is, Emilia Landulce noted in El Mundo, like Pepe in García Lorca’s play La Casa de Bernarda Alba: he never actually appears but he, the object of the daughters’ desires, is always there.

As his former Porto manager Julen Lopetegui says: “He’s strong in the challenge, of 10 challenges he wins nine, he’s intense, he has character, he is very conscious of his limitations and his qualities. Tactically he was very good, always right alongside the defenders when they needed him: cCentre-backs adore him. In a team that attacks a lot, that looks to play in the opposition’s half, that has a lot of players in front of the ball, he’s a basic need.” Lopetegui’s fitness coach described him as “an octopus”. Toril says his “chubby” face should not fool anyone: he is “very professional”.

Casemiro has improved on the ball, too; he reads the game better and has learned to position himself, angling his body in a way that minimises his weaknesses, allowing him to release the ball more quickly. Where once he might take three touches, relatively easy prey to teams pressuring him, he moves it on more quickly now. Or avoids trouble entirely. When he drops to face his own goal, more often than not he does not receive the ball at all and does not intend to either: the movement is designed, instead, to draw the opposition in, opening passing lines to Luka Modric and Toni Kroos.

“He is excellent playing facing the game: his switching of play, his inside passing,” Lopetegui explains. “It is harder with your back to goal and he’s worked on improving that; he also avoids finding himself in that position. He’s very conscious of his qualities but also his limitations, so he disguises them. He’s intelligent and that intelligence comes with humility.” Benítez would agree; he called him a “listener”.

“It was a joy to coach him; he listens, asks for advice, takes it on,” Lopetegui says. “His secret is the desire to improve, his willingness to adapt. He is everyone’s partner, helping them out: making adjustments, watching everything.”

He may not be the best player on the planet but, as Toril says, “Casemiro makes those around him better.”