The Portuguese manager signed the Chilean from Arsenal in January 2018, but he proved to be an expensive mistake and struggled to replicate the form he'd shown at the Emirates.
Sanchez left Manchester United this summer to join Inter Milan on loan, following in the footsteps of Romelu Lukaku, and Mourinho believes a change of scene could be the best thing for the 30-year-old.
“I felt him [to be] not a happy man,” Mourinho told the Telegraph.
“And I think in every job you have when you are not happy, it is not so easy to perform at every level.
“And maybe I am wrong. Maybe it was me who was not capable to get into him and to get the best out of him.
"As a manager sometimes you have the capacity to get the best out of the players, and other times you are not successful in that approach.
“But the reality is that I always felt [of Sanchez], ‘a sad man’. So probably in Italy he will recover this.
“I hope he can. I always wish well to every player.”
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