Manchester United goalkeeper David de Gea has come under scrutiny again after his errors contributed to his side’s FA Cup semi-final defeat by Chelsea.

The Spain international, 29, has made several high-profile mistakes in recent seasons, a far cry from when he was considered the best keeper in the Premier League and an ever dependable last line of defence for United.

“He’s unrecognisable from the keeper who won four player of the year awards,” said former United defender Phil Neville.

So what has changed for De Gea? Here, BBC Sport analyses the numbers behind his form this season and how they compare to other top-flight keepers.

(Note: All statistics are correct as of 19 July, 2020)

How is De Gea performing compared to other keepers?

After Spurs winger Steven Bergwijn shot straight through De Gea to score last month, former United skipper Roy Keane said he was “sick to death” of the goalkeeper’s errors.

That led to a passionate defence of De Gea by United manager Ole Gunnar Solskjaer, who labelled him as “the best keeper in the world”. But Solskjaer had to field more questions about his number one after Sunday’s FA Cup semi-final defeat.

First, De Gea allowed Chelsea striker Oliver Giroud’s flick to squirm past him and then saw what should have been an even more straightforward save – from Mason Mount’s speculative shot – slip through his grasp.

De Gea has made three mistakes which have directly led to goals this season, according to statistics provider Opta. Newcastle keeper Martin Dubravka and Liverpool stopper Adrian are the only players to make more.

But that statistic doesn’t tell the full story.

What reflects less favourably on De Gea is Opta’s ‘goals prevented’ figure.

This is calculated by taking away the number of goals conceded (excluding own goals and penalties) from the expected goals on target. An expected goal on target is an effort that Opta would ordinarily expect to result in goal.

De Gea has faced 32.3 expected goals on target and, after removing own goals and penalties, he has conceded 32.

That leaves him with a goals prevented figure of 0.3, which essentially means he has not prevented any goals beyond the saves you would expect the average keeper to make.

That figure looks even more ordinary when you compare it to the other Premier League keepers who have played more than 500 minutes this season.

Eleven keepers have prevented more goals than De Gea, including a player who also features in the debate surrounding the Spaniard – Sheffield United keeper Dean Henderson.

How does De Gea’s stats compare to Henderson?

Henderson, 23, has spent the last two seasons with the Blades on loan from Manchester United, impressing in their promotion from the Championship last season and their surprise success in the top flight this campaign.

Although Match of the Day pundits Neville and Alan Shearer were divided over whether Henderson should replace De Gea at the start of next season – with the former wanting to stick with De Gea and the latter calling for a change in Utd’s first choice – the Blades stopper is favoured by the numbers.

While he has made one error which led to a goal, Henderson also has a goals prevented figure of 9.3 – the third highest in the Premier League this season.

Henderson has kept 13 clean sheets this season, one more than De Gea and only fewer than Burnley’s Nick Pope and Manchester City’s Ederson.

Has De Gea declined in recent seasons?

One of De Gea’s most memorable moments in a Manchester United shirt was when the Spaniard made a whopping 14 saves – a joint Premier League record – in a 3-1 win at Arsenal in December 2017.

In that 2017-18 season, De Gea kept 18 clean sheets in the top flight, conceded 25 goals averaging out at almost a game and a half and prevented 13.7 goals.

That led to him again being named in the Premier League’s team of the season, but then he made a costly mistake against Portugal at the 2018 World Cup and his form has dipped since.

Based on Opta’s data, De Gea has conceded the same tally of goals that the model would expect the ‘average’ keeper to concede over the last two Premier League seasons.

In addition, De Gea only kept seven clean sheets last season – his lowest total since joining United – although that has improved to 12 this campaign.

“His performance levels have dipped and I’d be worried about his inconsistency,” said Neville, who was also United’s first-team coach in 2013.

“His credentials are still among the best in the world but at the moment he has lost all his confidence.”