Personally, I thought Harvey was mis-cast in The Alamo. Well, it's a fact. He was the wrong actor for Travis. There isn't a hint of the real Travis in his performance. He made no effort to learn anything about Travis. But he was so mis-cast that it wouldn't have helped.
His conflicted double-agent in A Dandy In Aspic called for stoicism and under-statement, instead we get such outlandish teeth-knashing and over-wrought emotions that it's impossible to believe he's a spy in the first place. Yet it's an excellent role for him. Instead of directing the film when Anthony Mann died, Harvey needed to be directed by a firm hand who would reign him in and help him modulate. The only thing wrong with the film is Harvey's over-wrought performance.
The only film I liked him in was The Manchurian Candidate. His personality is the character. He nails it. I can't imagine anyone else playing the part.