West Ham United have made some big mistakes when it comes to transfers in the past but David Moyes' decision to sell Issa Diop in the summer transfer window might go down as one of his worst.

Should West Ham have sold Diop?

Following the summer signing of Nayef Aguerd, Moyes opted to sell the centre-back to Fulham in a deal worth just £15m, as his contract at the London Stadium was due to expire at the end of this season. On the face of it, that is good business, particularly for someone who didn't start each game.

However, Thilo Kehrer would arrive less than a week later as cover for the departed Frenchman but has so far struggled to match Diop's performances, averaging a shocking 6.40 rating from WhoScored for his performances in the Premier League with the Hammers.

Meanwhile, Diop has established himself as a mainstay in Marco Silva's side as they target a surprise European finish in the Premier League, with the Cottagers currently occupying ninth place in the top flight.

The 26-year-old's 6.67 average rating from WhoScored is hardly very impressive but it is better than all of Kehrer, Aguerd and Kurt Zouma have managed in the Premier League this season, which suggests that Moyes foolishly weakened his central defensive options at the London Stadium.

Although the former Toulouse man would lose his regular starting spot in the Premier League under Moyes in the last two seasons, he was still a reliable option when selected, as is evidenced by his impressive 6.98 average rating in the Europa League last term.

He would certainly impress in his first season in a Hammers shirt, starring in their 3-1 win against Manchester United in 2018, which earned the defender the praise of Jose Mourinho.

He said: “Their centre-backs had a fantastic match. Congratulations to the scout who found Diop, a monster who dictated everything.”

While there is no doubt that Diop didn't live up to his potential at the London Stadium, making 121 appearances across his four years at the club, there is an argument that a better manager would have got the best out of the powerful centre-back, as we are now seeing under Silva at Fulham.

He now ranks first for interceptions, fourth for aerials won and sixth for tackles in Fulham's squad, which suggests he is more than playing his part in the Cottager's impressive season.

The sale arguably has shades of the aforementioned Haller, with Moyes having come in for criticism from various quarters for his treatment of the striker.

Indeed, the forward went on to flourish with Ajax after his West Ham exit, scoring 47 times in just 66 matches before earning a move to Borussia Dortmund, ultimately replacing the goal-laden Erling Haaland.

Now, Diop is showing that he is a more than capable defender, as Haller did, and as such, he could well have ended up having a big say in the Hammers' survival hopes. Unfortunately, as they travel to Craven Cottage next month, the Frenchman may well do so but for all the wrong reasons.