When Marissa Mayer became Yahoo's CEO, she lured her former colleague at Google, Henrique De Castro, to join her as Chief Operating Officer. Fifteen months later, she fired him, saying he was not a good "fit" after all. His severance package: $58 million. Did he earn his "golden parachute" after just 15 months of work? What does it say about the health of Yahoo, a major player in the high-flying world of communications technology? Felix Salmon, who blogs on finance for Reuters, picks up the story.