The Ex-Cubs Factor (or Ex-Cub Factor) is a seemingly spurious correlation that was seen as essentially a corollary to the Curse of the Billy Goat. Widely published in the 1990s, the hypothesis asserted that since the appearance by the Chicago Cubs in the 1945 World Series, any baseball team headed into the World Series with three or more former Cubs on its roster has "a critical mass of Cubness" and a strong likelihood of failure.