This paper focuses on examining the attendance of MLB teams that play home games in the same metropolitan area – duopoly teams. Comparisons were made between the determinants of attendance for duopoly teams and monopoly teams. While duopoly and monopoly teams share most of the same determinants, the estimated weights on some determinants differ. There is evidence that one duopolist’s attendance is negatively related to the other’s performance. Evidence is therefore provided that fans of one team respond to quality changes in the other team in a city.
Miller, Phillip, "Major League Duopolists: When Baseball Clubs Play in Two-Team Cities" (2006). Economics Seminar Series. 7.