The reason is because Robert Protsky was solid in everything he did. He was the ultimate actor, not only giving what was necessary to make the scene work, but also transforming so seamlessly into his characters to the point that you often didn't realize you were watching an actor at work.
Not blessed with traditional leading mans looks, Robert Protsky usually showed up as the judge, doctor, minister, father, grandfather, coach or neighbor. And even though his parts were often small, he was always memorable.
His contributions to Stephen King's, Christine, and the Oscar nominated films, Broadcast News, Dead Man Walking, Far and Away and The Natural, not to mention his numerous guest appearances on many popular television shows like Hill Street Blues and The Practice, make Robert Protsky a true talent whose presence in film, television and theater is greatly missed.