Jose did trust Miki. He eased him in, but in the 2nd season, despite playing him in every match, Miki played badly. Many fans on this forum were asking why Jose is repeatedly playing such a bad player. Soon after, Jose lost patience and gave up on him.
In the case of Fred, people need to understand that he is coming from a very very poor quality league.
He may have cost a lot, but he is a squad player. Unfortunately, in 2018, £50M is about the going rate for a decent player, of good age, with many years left on his contract.