De Bruyne isn't the kind of player to play a reactive (sit till something happens) type of player and Mourinho prefers those. He's an attack minded player and it was clear to everyone that he wasn't doing enough defensive duties at Chelsea and that's why he was sold by Mou. On the other hand, Pep uses his attacking and possession style of play to get the best out of a player like De Bruyne.
What? Mourinho loved Özil at Madrid and would love De Bruyne also, but Courtois slept with De Bruyne's girlfriend at the time which meant that one of them had to leave and De Bruyne chose to go. I can't stand Mourinho but pretty sure he had no say in the matter.