The Belgium forward was on Chelsea’s books for two years, but 18 months of that time was spent on loan and he left for Wolfsburg in January 2014 having started just twice in the Premier League.
De Bruyne has been linked with a return to England and Manchester City, with the reports??claiming this week City are prepared to break the British transfer record for the player this summer.
Wolfsburg say there have been no bids, but in the meantime the 24-year-old’s character has been questioned by his former Stamford Bridge boss.
“I’m happy for him because he’s a good kid,” several English newspapers quoted Mourinho as saying. “I wanted to keep him, but he couldn’t handle fighting for his place in such a competitive squad.
“He told me it was not in his personality to be competing for a position in the team. He needed a team where he knows he can play every game.
“I told him: ‘This is Chelsea, you are very young, you have Eden Hazard, you have Juan Mata, you have Willian, you have Andre Schurrle so I can not promise you that.’
“He told me he was not happy. He was not training very well.”
City, who have made no comment on the reports, are well-stocked in De Bruyne’s position having spent ??49m for Raheem Sterling to go with Jesus Navas, David Silva and Samir Nasri.