The versatile Dutchman has become a fringe figure at Old Trafford, with Jose Mourinho favouring other options across his back four and midfield.
As a result, Blind has been restricted to just one minute of Premier League football since starting the first three games of the season.
The former United and Barcelona boss said in the Mirror: “Daley Blind is better off going to Barcelona than staying with Man United.
“He is not even on the bench for United sometimes. Daley can play in more than one position and at Barcelona he would never be sat in the stands.
“He can operate as a central defender who builds up the play. He can be a defensive midfielder or an attacking left-back. Daley can do it all.”
Blind joined United from Ajax in the summer of 2014.
He has made 137 appearances for the club and is one outing short of 300 at club level.
Mourinho, though, has shifted Ashley Young to a left-back role this season, while several other options have been utilised at centre-half and Nemanja Matic drafted in for £40 million to fill a holding midfield berth.