Scott Cooper Explains Why Sienna Miller Was Cut From 'Black Mass' Johnny Depp, Joel Edgerton, Benedict Cumberbatch, Jesse Plemons, Kevin Bacon, David Harbour, Dakota Johnson, Julianne Nicholson, Adam Scott, Corey Stoll, Juno Temple — Scott Cooper's "Black Mass" is not wanting in characters or stars to play them, but a movie can only hold so much, and unfortunately one had to go: the underrated and very talented Sienna Miller. So, why was she left on the cutting room floor? “It came down to narrative choices,” the director told Boston Globe.