The first time Pep Guardiola encountered Joe Hart in a competitive game was in September 2013, when Bayern Munich wiped the floor with Manchester City in the Champions League. Hart was at fault for all three Bayern goals.

The first and third flew past him at the near post. For the second goal, Bayern lobbed a ball over City's defence into the penalty area. If the same ball had been played into the Bayern area, Manuel Neuer would have smashed through it and any opponent brave enough to get close to it. Hart reacted too late, and Thomas Müller scored easily.

You never get a second chance to make a first impression. Last year, Guardiola was in the crowd at Camp Nou as Hart made 10 saves – more than any other goalkeeper managed in the Champions League that season – to prevent City from being embarrassed by Barcelona. But Guardiola may be less impressed by saves than any other manager in the history of football. His attitude seems to be that if the goalkeeper has to make 10 saves, then the defence he’s supposed to be organising is already a disaster.

It reminds you of something Xabi Alonso once said about the difference between the English and Spanish understanding of midfield play. Alonso didn't understand why the academy midfielders at Liverpool would often highlight "tackling" as one of their best qualities. In Alonso's view, tackling was not a "quality", but a "recurso" – a recourse, something you only do as a last resort. If you find yourself launching into a tackle it's because something has gone wrong.

Distinct species

English football has always thought of the goalkeeper as a distinct species, the one who can use his hands and can’t really play football, more of an adjunct to the team than a true member of it. For Guardiola, the goalkeeper is a footballer who is allowed to use his hands. In England, goalkeepers are often complimented on being good shot-stoppers, but for Guardiola, goalkeeping is not about shot-stopping; it’s about stopping the shot from happening in the first place.

The important part of the job isn’t the bit where you dive around in the six-yard box trying to get your hands on the ball. The real work happens much further from goal, as you control the space behind your defence.

Another Guardiola insight is to think of the goalkeeper as an attacking player. Peter Schmeichel was the first to open English football's eyes to the goalkeeper's potential as an attacker, often launching counterattacks with spectacular overarm throws into the opposing half. Schmeichel had few imitators, because not many keepers could make those throws with the same speed and accuracy. As for the idea that a goalkeeper might be a playmaker with his feet, it never really occurred to anybody.

For Guardiola, the goalkeeper is the first playmaker. The Spaniard’s teams set out to dominate the ball from the first minute to the last. If the goalkeeper can’t be trusted to start every move with the right kind of pass, then the whole game plan is compromised.

That, at least, is the theory behind Guardiola’s decision to drop Hart. You can imagine that it is difficult for Hart to accept. He’s a 29-year-old international with two league titles, who has grown accustomed to thinking of himself as rather a good player. Now Guardiola is telling the world that Hart is perhaps good enough for a team that plays a primitive style, but not for one that wants to compete at the highest level.

The gaps between theory and practice only make things more excruciating. One such moment came in the 57th minute of City's 4-1 win at Stoke, when Willy Caballero, the man who is currently keeping Hart out of the team, miskicked a simple pass out of play. The gleeful Stoke fans sang "Joe Hart, he wouldn't do that".

For Hart, sitting in the stand, here was evidence that the deck truly was stacked against him. Nobody is ever going to mistake Caballero for Xavi. His chief merit in Guardiola’s eyes appears to be that he’s not Joe Hart.

But Guardiola is not just a coaching computer that makes decisions based purely on tactical and technical information. He considers the psychological and political dimensions, too.

So he understands that Hart is not just a decent shot-stopper with mediocre distribution skills. He’s the longest-serving player at Manchester City, the only senior English player, one of the faces of the Mancini and Pellegrini eras. He’s one of the leaders of the team.

Remember that Guardiola’s first decision as Barcelona manager was to get rid of Ronaldinho and Deco, who were among the team’s biggest stars. It wasn’t because they were bad players; it was because they were the leaders of a team that had grown lazy.

Intensity

Guardiola believed that he could not get the team to work with the intensity he was looking for if he let these senior players stick around setting the wrong tone. Kicking out Ronaldinho and Deco told the rest of the players that the time for slacking off was over. They would meet the new coach’s standards or they would find another club.

City’s performances last season were defined by a pervasive apathy and sluggishness that they couldn’t shake off even as their chances of Champions League qualification slid into jeopardy. They eventually crawled over that line, but Guardiola has chosen not to ignore the warning signs.

He can’t succeed in Manchester if City don’t rediscover their work ethic. It will be a while before City can hope to approach the technical and tactical level of Barcelona or Bayern, but there’s no reason why they can’t match their intensity from the outset. If a few sacred cows have to be slaughtered to focus everyone else’s minds on the job, Guardiola is happy to oblige.