Tottenham would probably have suffered the disaster of relegation from the Premier League if it were not for the decision to bring in Roberto De Zerbi for Igor Tudor, according to James Maddison and Conor Gallagher.

Spurs made the managerial change with seven games to go and the team in freefall after a run of one point from six matches under Tudor. De Zerbi rebuilt confidence and guided the club to survival, the 1-0 home win over Everton on Sunday ensuring that they finished above West Ham, who went down. De Zerbi’s record shows he had three wins, two draws and two defeats.

The club have a big summer ahead as they look to reboot the squad. They are expected to sign the centre-half Marcos Senesi and the left-back Andy Robertson on free transfers from Bournemouth and Liverpool respectively. The captain, Cristian Romero, is poised to leave and the goalkeeper Guglielmo Vicario could go, too. The most immediate emotions are relief and gratitude to De Zerbi.

“I am really happy for the manager, who has come in and steered the ship clear because without him it could have been doom and gloom,” Maddison said. “The appointment kind of saved the disaster from happening. Without that appointment, disaster could have maybe struck. But it didn’t and he takes a lot of credit for that.”

Gallagher added: “Like Madders said, thank God the new gaffer came in because he was the reason it turned around for the team and for me. From the first day or two he had everyone under his wing. Everyone trusted him instantly and everything he was doing. It was like: ‘Thank God he’s come in.’”

De Zerbi, who has lived with his backroom staff at the hotel at Spurs’s training ground, has made tactical tweaks. Under him, the team have pressed more effectively and forced more turnovers in the final third. He has fixed the midfield, using Gallagher to good effect as a No 10. But his biggest trick has been to restore the players’ self-belief.

It has been particularly pronounced with Gallagher, who was signed by Tudor’s predecessor, Thomas Frank, from Atlético Madrid in mid-January. Gallagher struggled under Frank before his form nosedived under Tudor. He was dropped from the starting XI by Tudor but has thrived since being reinstated by De Zerbi.

“It was obviously really tough for me and the whole team,” Gallagher said. “I was in and out, no confidence, didn’t feel great physically and then he [De Zerbi] came in and showed belief and gave me my confidence back. It just shows you how important confidence and rhythm is. And feeling physically as good as you can. Because I was low on confidence, the last manager wasn’t having me, the fans didn’t think I was any good.

“It was such bad times. We were losing most of our games, I wasn’t playing and when I played I didn’t do very well. I was playing out of position. I’d just moved back to England and I wanted to hit the ground running back and none of it was happening. I had to stay mentally strong and focused and have belief in myself, which I did.”

Gallagher mentioned how De Zerbi had shown him a video on YouTube to boost him. “It was titled ‘Bossing the midfield, Conor Gallagher’ – or something like that,” he said. “I’ve seen it before and he’s just there showing me in this meeting room. I found it really funny! He did a similar thing with a few of the other lads. That’s been one of his many ways to get players’ confidence back.”

Maddison also offered an insight into how De Zerbi has worked. “He’s just so passionate,” he said. “He’s been living at the training ground with his team. I go and stay there the night before every home game just to get a good night’s sleep. I’ve got too many kids and I can’t risk not getting a good night’s sleep. And he’s there at 9pm with all his staff. They’ve got the tactics board out. There’s six of them. It’s 9pm. We’ve already had like four or five meetings on each game. He’s just obsessed with football.”

Maddison’s season was wrecked by an anterior cruciate ligament rupture; he played only in the last three matches as a substitute. For the second campaign in a row, the club carried a massive injury list and it is plain they need to look into why.

A broader concern is a culture that has lacked accountability; one which is perhaps a little too comfortable. Is the five-star training facility somehow too nice? Frank and Tudor lamented how the team would fold when the setbacks came. De Zerbi knows he must instil greater resilience.

Conor gallagher

“We need to be responsible for holding ourselves to higher standards and demanding more from each other individually,” Maddison said. “It’s almost like looking in the mirror. ‘Have I been good enough? I should be better.’ And most weeks of the season I think that would have been the case. Lads need to kind of look at themselves … instead of blaming and whatnot.”

The Spurs nonexecutive chair, Peter Charrington, has criticised the previous regime, which was led by Daniel Levy, saying it did not put football success at the heart of everything. Levy, was ousted last September as the Lewis family trust took control and embarked on a radical overhaul of executive-level positions. Charrington, whose appointment was announced in March of last year, described the current situation as “not acceptable” but promised better times ahead.

“Last September, we recognised that something seismic had to change at Spurs,” Charrington wrote in an open letter to supporters. “The Lewis family stepped in and authorised a full reset. That decision was not taken lightly and it came later than it should have. But what has been put in motion is real and it marks a genuine break from what had come before.

“As part of that process, we discovered some uncomfortable truths. The qualities that make Spurs distinct – our football, our ambition, the connection between the team and its supporters – had been allowed to fade. Football success had not been driving our decisions. We did not have the right expertise in key roles. We did not build squads good enough to compete in the most demanding league in the world. Two 17th-place finishes in a row is not acceptable.”

Charrington, who insisted the Lewis family had no plans to sell up, made it clear that investment via the transfer market would be forthcoming. “We will build a squad, led by Roberto, with the right blend of experience, youth and leadership to compete at the highest levels of the Premier League and European football,” he said. “We will invest across multiple transfer windows.”