IT is a matter of the physical.
Diego Simeone was typically blunt and macho after he had led Atletico Madrid to the Champions League final. He thanked the mothers of his players for giving them "balls this big" before stretching his arms. He was not referring to the size fives said maters had left under Christmas trees for their offspring in years past.
Simeone was, of course, praising the courage and commitment of a side that came to London and dismissed Jose Mourinho's Chelsea.
This strength of will is not only a mark of his team but of a manager who always said he played "with a knife between his teeth".
However, the secret of Atletico's success under Simeone cannot just be measured in the spherical. This is a collective who have bought in to a system that makes huge physical demands on each player.
Much has properly been made of Simeone's record as a manager. He has won the Argentine Primera Division with both Estudiantes and River Plate and he guided Atletico into an era of unexpected success. With the world resigned to Spain being a two-horse race, Atletico have sprinted up the rails to win the Copa Del Rey last year, the Europa League and and the UEFA Super Cup. This season they lead La Liga and will meet Real Madrid in Lisbon inb the Champions League final on May 24.
Some of this success can be explained by numbers. The semi-finals of the Champions League offer more than clue. They were, of course, contested by Atletico, Chelsea, Real Madrid and Bayern Munich. In terms of possession statistics for the tournament, Atletico had the lowest figures out of the four. They also made more tackles and completed the fewest passes. Crucially, though, they run more than the other sides.
In the first leg of the semi-final against Chelsea, Atletico had more possession than Chelsea (62% to 38%) and cumulatively covered more ground (111,081 metres to 111,081 metres). This flies in the face of the cliché that the team without the ball runs more than the one with it.
Yet when Chelsea dominated possession on Wednesday (52% to 48%), Atletico ran 113,736 metres to the London side's 108,072 metres. The figures simply prove that Atletico work harder, tackle more and are willing to lose possession despite the prevailing orthodoxy that the ball - whether supplied by mother or by adidas - is all.
This relentless, energetic style is honed on the practice pitch. "We train in different ways according to the next opponent but always as if we are in a final," said one player.The Simeone way is to be tactically sound, with players told precisely what is expected of them in specific situations, but he offers enough flexibility for technique and improvisation. Atletico worked harder than the other Champions League semi-finalists yet can also boast of having the artist as well as the artisan. Diego Costa, Koke and Gabi are technically excellent but also press, tackle and run.
"One of the triumphs of Simeone is that he has done an awful lot with limited resources," said Jimmy Burns, the author of La Roja, a Journey Through Spanish Football. "Of course, Atletico do have money but not on the same scale as Real or Barca yet they have become more than just competitive. This is an example of everyone buying into an extraordinary team ethos. The fans, the players and Simeone have come together to create a powerful chemistry. It is impossible to sit in the Vicente Calderon and not be affected by it. It is palpable."
Burns points out the Simeone was known for his tough character on the pitch as an Argentine internationalist with 106 caps.
'He has, though, shown a deft touch with handling players. Every interview with an Atletico player contains some praise for the manager," said Burns.
This is in contrast to Mourinho who could not control a notoriously fractious Real dressing-room and is now encountering dissent at Chelsea. Eden Hazard, the Belgian midfielder, has accused his manager over his tactics. "Chelsea are not set up to play football," said the Belgian. "They are set up to counter-attack."
Many commentators have made the same observation about Atletico but not one of Simeone's players would make such an observation in public. They believe in Simeone, in his methods and in his character. It is a matter of respect.
Burns points out that the Argentine extends this trait in in his dealings with other clubs.
"It was no surprise he was respectful of Jose Mourinho before the second leg," said the author. "That is how he conducts himself. He is never rude or outspoken before playing Real or Barca, for example," says Burns, who wrote a marvellous history of the Catalan club.
"It is significant that when Atletico knocked Barca out of the Champions League that the Barca fans stayed on to applaud Simeone and his players. He is respected in Spain," says Burns.
Simeone's reputation, of course, has travelled beyond the borders of Spain and not just because of a playing career that was marked with a strong technique and a sly ability to both nullify and provoke opposing players, most famously David Beckham at France 98.
He has now broken into the elite group of managers. He has strong selling points: his teams over-perform in comparison to the financial strength of his direct rivals, he is tactically astute, his players have faith in his methods. And he wins.
Radomir Antic, the Serb who managed Atletico in 1991, believes that Simeone immediately grasped the ethos of the club when he arrived in 2011. The Argentine, of course, played for the club in two spells, winning La Liga in 1995-96.
"He has moulded an outfit of success-hungry players who have subdued their egos for a greater good, which is the present generation's biggest victory because it is not an easy task," said Antic. "He has struck a common chord between the pitch and terraces."
Burns agrees, pointing out that a side that has used only 17 players this season still has the energy to pursue two great prizes.
Atletico are four points clear in La Liga with three matches to play. They are in the Champions League final, 40 years after they reached the European Cup final by defeating Celtic in the semi-finals.
They may have to avoid defeat at Barca in the last match of the season to take the domestic title. They will have to overcome Real to win the European crown. The ball - whether provided by nature or sponsor - is at their feet.