Manchester United manager Ole Gunnar Solskjaer has done a tremendous job of eradicating the many mistakes his predecessors made in the transfer market, but there are still a handful of underperforming flops lingering around the club.

During his two-and-a-half-year stay as Red Devils boss, the Norwegian tactician has shown the door to the likes of Alexis Sanchez, Marouane Fellaini and Matteo Darmian, replacing them with astute purchases that have transformed the fortunes of the 20-time English champions.

However, Solskjaer's squad overhaul is not quite complete yet. And one player who continues to raise question marks due to his disappointing displays is Diogo Dalot.

The 22-year-old defender arrived at Old Trafford back in the summer of 2018 from boyhood club Porto via a £19.8m move, and former United boss Jose Mourinho couldn't hide his delight after the deal was concluded.

"Diogo is an extremely talented young defender with all the qualities to quickly become a great player for this club," said Mourinho at Dalot's unveiling.

"He has all the attributes that a full-back needs: physicality, tactical intelligence and technical quality, combined with a Porto academy mentality which prepares players for the maturity they need at the professional level.

"In his age group, he is the best full-back in Europe, and we all believe he has a bright future ahead of him at Manchester United."

However, things have not worked out as planned for the Portugal international. During his first two seasons with United, Dalot made just 13 Premier League starts and largely failed to impress during his time on the pitch.

Things started to look up for the youngster last term, though. He joined Serie A giants AC Milan on a season-long loan and played a pivotal part in the success that Stefano Pioli’s charges enjoyed.

Throughout his 12-month spell at San Siro, Dalot made 33 appearances in all competitions, achieving a highly respectable 6.76 WhoScored rating along the way.

And £25k-per-week earner's contribution to the Rossoneri was sizeable, making 1.5 tackles, 1.2 interceptions, and 1.8 clearances per league game as Milan finished in second place in the Serie A standings.

Nevertheless, he's struggled to replicate that sort of form since returning to English shores. In his five appearances for United during the opening weeks of 2021/22, Dalot has been awarded a rating of just 6.67 for his exploits, highlighting his unsatisfactory output.

The right-back's performances levels have seen his market value plummet to just £9m despite his age and current contract not expiring for another two years, illustrating how a much-celebrated transfer has turned into a nightmare.

At 22, the best could still be to come from Dalot and he will have ample opportunity to finally fulfill his potential, but he will have to improve his game quickly if he's to get many more chances in a United shirt.

And, in other news...Rob Dawson reveals worrying Man Utd transfer update, Ole may be concerned