The Red Devils managed to see off competition from Premier League leaders Manchester City for the signature of Sanchez in the January transfer window.
Manchester United made Sanchez the best paid player in the club’s history following his switch to Old Trafford from their Premier League rivals Arsenal.
The Chile international has scored two goals in 12 games in all competitions since his move to Manchester United.
Sanchez has been criticised for his ineffective performances in the Manchester United team after the Red Devils crashed out of the Champions League round of 16.
However, former Manchester United defender Parker has put his finger on why Sanchez has found it difficult to adapt to life at Old Trafford.
“With Sanchez you have to look at the team more than anything,” said Parker, speaking to exclusively 888sport. “At Arsenal he was always on the ball and tracking back.
“He’s one of those players who you need on the ball as much as possible. He needs time with it.
“When you see those stupid stats saying how many times he has given up possession when you look at him as a player he’s a player’s player because of how hard he works and how much he wants the ball.
“So of course he’s going to give it away more because he’s on the ball more. As good a player as he is he needs a team around him, a good team, who will find him in the final third.
“He’s getting frustrated and quickly shows his emotions and that is a problem. He’s no longer in a team that passes as much as Arsenal.”
Manchester United won the Europa League and the League Cup in the 2016-17 season under Mourinho last term.
The Red Devils are on course to improve upon their sixth-placed finish last term as Manchester United sit in runners up spot and two points ahead of Liverpool FC.
Mourinho could finish his second season at Old Trafford with some silverware if the Red Devils beat Tottenham to reach the FA Cup final.
Read the full 888sport interview with Paul Parker, including his thoughts on Mourinho’s tactics in charge of Manchester United
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