Succeeding a Legendary Coach: A Preliminary Investigation into the NFL Betting Market

Some coaches are so successful and have such an impact on their team that they are considered "legendary." When they step down from their position and the team transitions to a new head coach, there will likely be a great deal of uncertainty concerning how the team will perform in this new situation; thus, it may take time for the betting markets to adjust. The purpose of this study is to investigate the efficiency of a sports betting market for the rare situation in which a legend steps down from the head coaching position. Data from the National Football League are analyzed using a novel implementation of classification trees to determine if and when a market inefficiency exists in the subsequent season. We find a potential bias early in the following season before the market appears to adjust to the new coach.