I don't think you can say that a trial was permeated with unfairness without it being a reflection on the judge. The judge is there to control proceedings so that the accused is fairly tried.Why blame the judge though?
If prosecuting counsel repeatedly ignores the judge's directions, is there anything short of declaring a mistrial that the judge can do? Perhaps declare counsel in contempt of court? What would happen then? Would the case continue as before or would counsel be replaced? Or would the contempt issue necessitate mistrial anyway?