According to Atlético Madrid's captain, Gabi, when Diego Simeone turned up at the Vicente Calderon two days before Christmas 2011 the team, dangerously close to the relegation zone, were "mentally sunk".

Since then, they have won the Copa del Rey, beating Real Madrid in the final at the Bernabeu – the first time they had defeated their rivals this century; claimed a seemingly impossible league title; reached a first European Cup final in 40 years, which they were seconds away from winning; and achieved their biggest derby victory since 1947.

Avoid defeat against Malaga this Sunday and they will be top of the table at Christmas.

So it is easy to see why Chelsea believe Simeone is the ideal candidate to take over at Stamford Bridge. There is even a touch of Jose Mourinho about him; the good Jose Mourinho, that is. Charismatic and convincing, he has become the figure at the Calderon, close to his players and to fans, inspiring them and mobilising them.

Watch him at games and he conducts the crowd as well as the team. Not least because in his mind those two go together: communion is key.

Completely transformed

Rarely, if ever, can a manager have so completely transformed a club and it is not as if he relied on huge signings.

When Atlético won the title they did it with the same players as before, except they were not the same players at all.

Simeone has not so much got the best out of his players as got more from them than they, or anybody else, ever thought they had.

There is much about Simeone that makes him attractive to Chelsea. Few managers transmit the energy he does; his footballers talk about the belief they have in him and the belief he has deposited in them.

The intensity with which they play is striking, so too the collective solidarity. They are supremely competitive, fit, strong, organised and more talented and tactically astute than those descriptions usually allow. Simeone called Atlético an “uncomfortable team” while an opposition coach put it more bluntly: “horrible,” he called them.

“They’re a big team that runs like a small one,” the Eibar manager, Jose Luis Mendilibar, admiringly said.

When Luciano Vietto joined Atlético in the summer, he admitted he could barely cope with the sessions, so tough were they. As he staggered across the grass, pouring water over himself, dizzy, exhausted and barely able to stand, Simeone and his assistant, German Burgos, laughed.

Simeone’s achievements have been an enormous overachievement. It is not only that Atlético were the first team to take the title off Real or Barcelona in a decade, it is that it had become legitimate to wonder if anyone else would do so ever again.

Now, incredibly, they aspire to repeat that this season, even though they will not admit as much. Publicly and privately, Simeone insists Atlético cannot truly compete with the big two but there they are, competing. Game by game, as Simeone insists. It is his mantra.

“Game by game is the life of the man on the street: it’s day by day,” Simeone said when they won the league.

“We see ourselves reflected in society, in people who have to fight daily to keep going. As soon as we stop fighting we have no chance. People identify with us, we’re a source of hope to them. With the tools we have, the resources we have, we have been able to compete with bigger opponents.”

He repeats often that they have done it with a budget a quarter of the size of Real’s. The argument is obvious; imagine, then, what he would do with Chelsea’s money.

It would be natural enough for Simeone to have thought the same. And Chelsea, the team to whom he lost his best striker, is attractive of course, while the pull of London is significant. But in that message lies the flaw, too.

Chelsea is not Atlético and at Stamford Bridge Simeone would not be the same. He would have to reinvent. He would have to rethink too; his imagined career path always prioritised Italy over England.

There are reasons to go to Chelsea but there are also reasons not to. There is the blunt fact that, money aside, Atlético is probably a better club to be at right now; second in the table only on goal difference, well placed in the Champions League, finalists 18 months ago, the team who tore Chelsea apart.

An obsession

There are challenges ahead, both immediately and in the long term, the Champions League especially.

The year 2014 hurt, Sergio Ramos’s 93rd-minute goal a source of motivation, maybe even the seed of an obsession.

Beyond that, this is a young team and there is talent emerging from below: Koke, Saul, Thomas and Oliver.

There is also the fact that Simeone is a motivator who does not speak English, a communicator whose communication would be curtailed in London, at least to begin with. And yet there is more to it than that, certainly for Simeone. It is deeper. It is that this is his club now; it always was.

When Atlético scored against Real last season, the ballboy near the bench ran and leapt into Simeone’s arms: it was his youngest son, Giuliano. His other son, now at River Plate, began his youth career at Rayo Majadahonda, barely 50 metres from the club’s training ground.

“I’m not sure if Simeone is the only person who could have rescued us but he was the best placed,” Gabi says of his arrival.

Here was the man who had captained them and won the double with them, scoring the goal that clinched the league title. His charismatic authority began there, and he understood and used symbolism.

No one else had the spiritual significance he had, and “spiritual” really is not too much of an exaggeration. Winning has made even more of a leader of him, almost a philosopher around whom the club is being built.

Simeone is a man identified with Atlético, who signed a new contract until 2020 and still has a sense of mission about him, not only on the pitch.

A legacy

Success has brought restructuring at every level; the club has improved with the team. Chinese investment has arrived. The intention is to move to the new La Peineta stadium in 2017; the strategy – and it is one that was discussed when he renewed his current contract in the summer – is for him to lead the club there.

Nothing is impossible and plenty of managers have built only to turn their backs and walk away, leaving a legacy for others. Romanticism is easily ripped up, of course.

But depending on what happens during the rest of this season, this feels a little soon, and it would be hard for him to walk away. There is so much more to do, at his club and on his terms. There is a word Simeone uses often: pertenencia, or belonging.

He belongs at Atlético; he would not belong in quite the same way at Chelsea.

Guardian Service