Alexis has spent this season on-loan at Inter Milan.
He told BBC Sport: “I say things as they are and in my opinion.
“Mourinho is one of the best coaches in the world in the way that he coaches, how he studies videos, the way he goes about things.
“But then, within the group there was that feeling that you were in the team then out.
"Sometimes I didn't play, then I did, then I didn't and as a player you lose confidence, each player lost their confidence, do you understand?
“And then an atmosphere was created that wasn't healthy.
“Sometimes I'm playing well and I score a goal and he took me off. And I'd say, 'I love football, I love football.'
“I've played football since I was five and if I have the ball taken away from me, it's as if I lose my joy. I'm like that."