Why is Clint Frazier always the odd man out?

For example, he can have a 3 home run, 10 RBI game, while a mediocre call up strikes out 3 times, yet Frazier is then the one that gets sent down with the mediocre player gets to stay! If the Yankees clearly don’t need him, why haven’t they traded him away yet?
Update: *while the mediocre player gets to stay
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