I don't think that fans get to make those decisions.
Without knowing anything about Udinese or their manager, I'll assume that they have their own way of playing and that they have a specific role in mind for Miller, which may be different to what he is used to, so he'll need time to learn that. He'll also need to learn how to communicate effectively, so hopefully he's getting paid enough to afford a private Italian tutor for a couple of hours a day. He was also injured and needs to get his match fitness back, so there are a variety of factors that may be limiting his game-time.