Pettine must have been watching a lot of film and have some input on what he can do with what's left. Randall may have been a cancer, but you don't jettison a guy who last year was one of your best (on a bad squad) unless there's someone else who Pettine believes can step in. If Randall had been that valuable, they would have kept him and put him on notice to clean up his act.
After watching Hayward, Hyde, etc., leave and do well, I'm going to optimistically believe that Pettine is going to do better with whomever's left.