I honestly hope not. At this point you aren't going to get squat for him. Just try and hope that he fixes whatever the hell went wrong this season, next season.
What would be even WORSE is trading him for scraps, only to see him revert back to form. Miller has been one of the better pitchers in baseball for most of his career. And even then you probably overpaid. The worst thing you can do now is trade him for garbage.