Sienna Miller and Giancarlo Giannini have joined The Catcher Was A Spy, the Ben Lewin-directed drama that stars Paul Rudd, Guy Pearce, Paul Giamatti and Jeff Daniels. Robert Rodat adapted the script from Nicholas Dawidoff’s bestselling book that tells the true story of Moe Berg, a major league ballplayer who was an important spy against the Nazis in WWII.