Made sense to me. Do you disagree?
Ben Stiller is not a straight man. Just because he's not funny doesn't make him a straight man.
It's really very simple. A straight man is part of an act. He delivers straight lines to a comedian, who then delivers the punch lines. In simple terms, the straight man provides the foundation for the joke, whereas a guy like Ben Stiller is
the joke. So, for instance:
Straight man: "Who was that lady I saw you with last night?"
Comedian: "That was no lady, that was my wife!"
Audience: (peals of laughter)
In contrast, this is Ben Stiller:
Ben Stiller: "Ow, I caught my penis in my zipper!"
Audience: (confused silence)