I don't know if the article is too long, but "due to sexist bias" is certainly too short to give it justice. The specific problem with stack ranking is the one

I don't know if the article is too long, but "due to sexist bias" is certainly too short to give it justice. The specific problem with stack ranking is the one-on-one ranking method. I'm absolutely convinced that I myself would succumb to all sorts of biases when asked to rate people like that: I'd tend to think the silent, introvert guy who stays late and has no fashion sense is smarter than the outgoing jock leaving at 5pm sharp to be with his family. I'd somehow convince myself that the guy I enjoy eating lunch with is more important than the Belgian guy who doesn't speak english well enough to socialise... The article makes a similar point: “My observation was whoever was the best orator got their people ranked higher.” On aggregate, it's quite obvious that these biases could amount to gender-specific discrimination, even if not a single evaluator had gender on their minds.