It was transfer deadline day at Tottenham Hotspur and, not unusually, tensions were running high, particularly among supporters, who had seen their team take three points from the opening four matches and were conscious of what looked like a glaring flaw in the squad.

With Harry Kane the only recognised striker, the call for reinforcements up front pounded like a migraine. Even Mauricio Pochettino had made it plain the week before that he needed an alternative. “It’s like when you are in love with a lady – there are a lot of women around the world but you want only one,” the manager said.

The one Pochettino wanted was Saido Berahino of West Bromwich Albion, a quick and clinical player whom he felt would fit easily into his system. That move fell apart amid acrimony but Daniel Levy, the Spurs chairman, had another suggestion.

Levy told Pochettino he could get Charlie Austin from Queens Park Rangers and he believed he could do so for less than the £15m fee that had been quoted. Austin had scored 18 Premier League goals the previous season. He had earned an England call-up. At the very least, he looked like a decent option in Tottenham’s hour of need.

Pochettino was not interested. He told Levy that Austin, good player though he was, would not represent a fit for his team. He would prefer to make do with what he had, to adapt other players if necessary. He would not add for the sake of adding and, for him, it was not only to do with quality over quantity but instead, specific qualities.

The Spurs manager talks every week about his philosophy, which is a modern, more worldly take on plain old style, and his conviction in it is total. Since his arrival at White Hart Lane in June of last year, he has sought to shape a squad who can buy into his way of playing and his broader ideals about camaraderie and togetherness.

Profiling has been key. Pochettino wants energetic players who can be tactically flexible, particularly in attacking areas, to carry out his high-pressing game plan. He has also tried to ensure the club signs good people, as well as good players.

There was a backlash when the transfer window closed without the new striker, a collective fretting about the horrors that would befall the club if Kane were to be injured. Pochettino, though, did not care and he even argued the toss. “Much has been said about us only having one recognised striker in Harry but I don’t accept this at all,” he said. “The positional play of today’s forwards means it’s too simplistic to look for goals from any one position and playing a fluid style means players switch. Also, we secured Son [Heung-min] and Clinton [Njie] in the knowledge that we may not be adding any other forward.”

There is a boldness about Pochettino and the manner in which he believes in his methods, the feeling he is entirely prepared to stand or fall by them. Right now, he is standing, and pretty proudly, too.

Tottenham have momentum. Since the beginning of September, they have won six and drawn three of their nine league fixtures, while balancing the demands of the Europa League, in which they have qualified for the last 32. They have transformed people’s perceptions. When the window shut, practically no one thought they would contend for a top-four finish. Now, it would be a surprise if they did not. And, above all, they have strong identity and belief.

Tottenham have written the manual on false dawns and it is invariably risky and-or foolish to make grand statements about them. But here goes. There is the feeling that, under Pochettino, they have shed their soft underbelly, there is a clearer sense of shared purpose and the general impression of permanence.

When they beat Chelsea at White Hart Lane last season, in a 5-3 thriller, it was considered a shock result. If they do so again on Sunday, it will be nothing of the sort and that is not only because of Chelsea’s extraordinary slump. If Tottenham win, they will be 13 points ahead of them.

“Pochettino is trying to change the culture of the club and that was needed,” Mousa Dembélé, the in-form midfielder, says. “The mentality has changed and you can see the difference. We play more pressing and we try to be sharper whereas in the past we were two goals up and then we’d draw. This season, people talk more. You have to be awake. There has been a big change.”

Pochettino is warm and big-hearted, and it is a fair bet the public do not see this side to him via his broadcast interviews. He is tactile, always hugging people and puting his arm around them, and he has emphasised the creation of a family environment. When he arrived last season, he was keen to take all of the staff out to dinner. For him, it is not just about the team; rather the team around the team.

But there is a ruthless edge. If Pochettino feels a face does not fit, it is bumped towards the exit. He named Younès Kaboul as the club captain in September of last year but he soon realised the centre-half, despite his leadership qualities, could not be relied on defensively. Kaboul barely played from November and he was sold in the summer.

The squad were also purged of others Pochettino could not depend on, including Étienne Capoue, Paulinho, Vlad Chiriches and Roberto Soldado, and there have been those to depart after they were ostracised from the first-team group. At the start of last season Benoît Assou-Ekotto was banished – although that was more to do with a bitter row between him and Levy – and, at the beginning of this, it was Aaron Lennon and Emmanuel Adebayor.

With Pochettino, there are different levels of being bombed out. Soldado, for example, was allowed to come and go as he pleased over the summer, using the training ground facilities to maintain his fitness as he awaited a move. With Assou-Ekotto, Lennon and Adebayor, the regime was less forgiving.

But in each case Pochettino did not say a bad word in public about the players, despite repeated questions from journalists. There was nothing vindictive about the decisions; they were merely cold, calculating and, to his mind, necessary.

This is now his squad and everyone is on board, apart from possibly Andros Townsend and Federico Fazio. Townsend earned an unprecedented public rebuke from Pochettino after he argued with the fitness coach Nathan Gardiner during the post-Aston Villa warm-down on 2 November and he has not played since. Fazio’s only appearance of the season came in the Capital One Cup defeat to Arsenal on 23 September and, when Pochettino took a 21-man squad to Baku for Thursday’s decisive 1-0 win over Qarabag in the Europa League, the centre-half was kept in London, quietly and without explanation.

In some respects, Pochettino has got away with the overreliance on Kane – it remains a very big relief the 22-year-old has stayed fit. But there is also the sense Pochettino has made his own luck through hard work and clarity of vision.

The season’s positives have been plentiful. The new additions, Toby Alderweireld, Dele Alli and Son have been excellent, as has Kane again, and Eric Dier has been a revelation in defensive midfield. The squad have a lean and hungry look, they invariably cover more ground than their opponents and the heartening faith in young English players continues. It is worth remembering Pochettino’s net spend on transfer fees across three windows is £5.7m.

There are people at Tottenham who believe Pochettino did not get the credit he deserved last season, when he took the club to the Capital One Cup final against Chelsea and fifth place in the league with a squad e was not entirely happy with. He is now. And it shows.