He's making a good case. When he is off his game the Warriors look pretty mundane, so he is obviously valuable.
I think there is plenty to be said for Cleveland's defense though. Committing to "you have one job; guard him, if help comes, keep guarding him anyway, and don't bother with offense" and sticking to it is pretty strong. I was actively watching for it last night, and I didn't see Dellavedova run the court once when the Cavs had the ball. For a guy who is clearly as intense as they come to do that takes a whole level of discipline that is hard to come by.