(Credit: Wiener Staatsoper/InArt Management/Marius Baragan/Kristen Hoebermann/Opus Artist) Every year the Metropolitan Opera includes certain elements of surprise in its season planning, whether in repertoire or in casting choices. Sometimes those casting choices are unexpected and include important returns to the stage. This season, OperaWire is spotlighting six major artists that have not performed on the Met stage in years and {…}