Do MLB Players Perform Better Against Their Former Team?

Abstract: Being traded from one team to another in professional sports is popularly thought to impact a player’s performance. Prior research has suggested that players may have an elevated level of performance and aggression after a trade occurs. The present research looks to understand how MLB players perform against their former team after being traded by investigating post-trade performance against their former team. Data were collected from Baseball Reference for players traded mid-season from the 2013-2019 MLB seasons to find how players’ offensive performance changed against their former team when at their new stadium and the former stadium. The results show that there is some evidence that being traded affects younger and older MLB players differently. Younger players perform better in their new stadium while older players perform worse in the new stadium. The variation in effect may be attributed to economic mechanisms such as informational advantages and different levels of effort exertion.