The Red Devils signed the Chile international in a swap deal from Arsenal in the January transfer window as Henrikh Mkhitaryan moved in the opposite direction to north London.
Sanchez netted three goals in 18 games in all competition in the second half of the 2017-18 season to raise questions about the South American’s form.
The 29-year-old’s struggles have continued in the current campaign and Sanchez failed to get on the score-sheet in his first six appearances in the Premier League this term.
The Chile international scored Manchester United’s 90th-minute winner in a 3-2 comeback victory over Newcastle United at Old Trafford in their last fixture before the international break.
Sanchez established himself as one of the best players in the Premier League during his three and a half seasons at the Emirates Stadium.
However, the South American forward allowed his standards to drop in his final 18 months at Arsenal as Sanchez sought to secure a move after failing to agree a new deal with the north London outfit.
Former Manchester United midfielder Scholes has questioned whether the Red Devils should have recruited Sanchez in the first place.
“I know he has qualities and has been a good player but I never saw him as a United player,” Scholes told ESPN.
“I saw him as a bit selfish, someone who played for himself sometimes. I didn’t think he was a player that we needed, especially for that type of money.
“How would we be able to get rid of him now when he earns those wages? The signing felt like it happened just to stop Man City signing him.
“It feels like every player who comes into the team struggles. I feel like we could sign Lionel Messi at the moment and he’d struggle in this team.”
Sanchez scored 80 times in 166 games in all competitions during his spell at Arsenal after the Chile star moved to the Gunners from FC Barcelona in a £35m deal in the 2014 summer transfer window.
The Chile international won two FA Cup titles during his spell at the north London club but Sanchez was unable to fire the Gunners to title glory.
The South American forward started his career in Europe with Udinese before the 29-year-old moved to La Liga giants FC Barcelona in the 2011 summer transfer window.
The Red Devils star was part of Mourinho’s team that lost 1-0 to Chelsea FC in the FA Cup final at Wembley last term.
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