And, in both of those cases, the people making the arguments are probably doing it to vindicate a viewpoint, rather than actually look at it with any sort of reasonable expectation that they might be wrong.
Anthony in New York has been a good example: The Knicks are typically terrible in spite of his play, not because of it. The numbers bear that out, but it doesn't fit with the storyline that people concoct around hoops, so the converse is parroted instead.
edit to edit: I'm too young to have seen McGinnis, so I'll take your word for it.