Not all of his movies were great, but he made more than his share of great movies -
12 Angry Men, Long Day's Journey Into Night, Fail Safe, The Hill, Serpico, Network, Dog Day Afternoon, Prince of the City, The Verdict. Not as appreciated as he should have been, in my opinion.
If you compare him with directors who only made one movie every ten years, like Malick or Kubrick.. . .
He was best at drama enclosed in a small physical or metaphorical space - a room, a family.
He finished strong with
Before the Devil Knows You're Dead