“Not the perfect goalkeeper but good enough for Manchester United.”

United signed the 27-year-old Cameroon goalkeeper from Inter Milan for an initial £43.8m after David de Gea left when his contract expired after 12 years at the club.

The pressure was immediately on Onana, who has become only United’s third clear number one goalkeeper since 2005.

Either Edwin van der Sar (2005-2011) or De Gea (2011-2023) played 88% of United’s games over the past 18 seasons.

But United’s start to this season has not been great, and neither has Onana’s. They have conceded 10 goals in five Premier League games, more than winless trio Sheffield United, Everton and Bournemouth.

He also let a soft Leroy Sane shot squirm past his body to give Bayern Munich the lead on their way to a 4-3 win over United in the Champions League on Wednesday.

“It’s all been focused – as it happens very often – on one incident: the mistake of Onana,” said journalist Guillem Balague on the BBC Radio 5 Live Euro Leagues podcast.

“It was 19 shots from Bayern, nine from Man United. That tells the story. The focus has been on one mistake.

“The big picture is a team that don’t defend very well. Man United don’t have a clear idea of how they want to defend.”

When Onana replaced De Gea this summer it was largely seen as Erik ten Hag, Onana’s former manager at Ajax, wanting a goalkeeper who was better with the ball at his feet.

Last season Onana only conceded 36 goals in 41 games, keeping eight clean sheets in Inter’s 13-match Champions League run, which culminated in them losing 1-0 to Manchester City in the final.

He conceded 10 goals in Europe’s top competition from shots that came with an expected goal tally of 17.8. The 7.8 goals he effectively prevented was the highest total in last season’s competition.

“He’s presented as this playmaker in gloves, but there’s more to him than that,” said reporter James Horncastle.

“I don’t think he’s been signed exclusively for line-breaking passes and helping United beat the press. They want a shot-stopper as well instead.

“He kept Inter in games last season with his hands, not his feet. In time we’ll see the true value of Onana.

“But right now, as with everything at Manchester United, it’s a club that doesn’t have a stable environment, everything is highly pressurised. It’s not an easy environment to come into.”

Among the 23 goalkeepers to play in the Premier League this season, Onana is joint sixth for saves (20) but only joint 13th for percentage of shots saved (67%).

He is fourth for passes (174) but only seventh for successful passes (129). His passing accuracy of 74% sees him 14th – and he ranks bottom for passing accuracy to the opposition half, with only 15%.

United have conceded three or more goals in three consecutive games for the first time since December 1978.

After the error at Munich’s Allianz Arena, Onana came out to speak to TV to say he “let the team down” and they lost “because of me”.

Horncastle said: “He’s a big character. He showed mettle in coming out and claiming responsibility even though he wasn’t responsible for the entire defeat. A midfield that goes missing is also culpable.”

Balague said: “I’ve asked three Premier League goalkeepers about what he did wrong and they all said the same thing – to dive on the left side to get the ball you have to take a step to your right first which he doesn’t fully do.

“From that moment everything was wrong, he was late going down, he didn’t know whether to push the ball away or hold it and made a technical mistake.

“Because he’s not the smoothest technically he makes little mistakes that sometimes cause goals. He’s fantastic with his feet. Sometimes he does saves for the gallery but he does save impossible balls too.

“He’s not the perfect goalkeeper but good enough for Man Utd.”

However, that technique – which three English top-flight goalkeepers criticised – has changed the way Ajax’s young goalkeepers are coached.

“Ajax’s sporting science and analytics department looked at his technique when it came to diving and realised it was unorthodox,” said Horncastle.

“He said it’s ‘because I think I can get to the ball quicker this way’. They wired him up to see if it was the case and they found out he was right.

“With his technique he could get down quicker than the technique they were teaching in their academy.

“So Ajax began teaching their young goalkeepers Onana’s technique as an optional extra because he’d proven to them it works.

“We can all focus on what happened in Munich, but over the course of his career that technique is one of the reasons he is where he is.

“I thought United underpaid for him when you see the price of Kepa, Alisson and Ederson.”

Onana’s £43.8m move made him the third most expensive goalkeeper ever – although well behind the world-record £71m Chelsea paid for Athletic Bilbao’s Kepa Arrizabalaga in 2018.

Alisson’s £66.8m move to Liverpool from Roma the same summer ranks second. Ederson’s move from Benfica to Manchester City in 2017 for £35m is next, after Onana.

Some fans mischievously pointed out on Wednesday that De Gea – who won a joint record four Manchester United player of the season awards (2014, 2015, 2016 and 2018) – is still available.

He had been linked with Bayern and Real Madrid during the summer – to cover the injured Manuel Neuer and Thibaut Courtois respectively – but moves never materialised.

The 32-year-old remains a free agent about six weeks into the season, and can join a team outside of the transfer window – with Real Betis reportedly interested.