Document Type


First Faculty Advisor

Alicia Lamere


Baseball; Psychology; Twitter; Sentiment; Pressure

Rights Management



Performance under pressure and psychological momentum are well-documented topics in sports psychology, but most research focuses on “in-game” pressure. This study views pressure more broadly to examine how the external pressure of fans, quantified using the sentiment of tweets mentioning the players, can affect how MLB players perform. Although external pressure is intangible, it can impact a player’s psyche and performance. This investigation focuses on players Chris Sale and David Price. A new process was developed leveraging the Vader package in Python that can generate tweet sentiment to compare to several performance metrics from Baseball Reference. Results proved to be promising with correlation analysis pointing to some association between sentiment and performance. There was also an observed difference in how both players handled the pressure depending on whether they played for a small or large market team. An anecdotal study of the 2018 season showed even more interesting differences between Sale’s and Price’s performance and Twitter sentiment. Price’s performance and Twitter’s sentiment moved in a cyclical manner throughout the season whereas Sale’s results were much more consistent and less sensitive to change. Finally, a study focused on the impact of both pressure and past performance on future outings showed results consistent with past studies on the subject. For example, Sale was most likely to perform well under pressure if he preceded the start with a very good or bad outing rather than an average outing. Information like this could be useful for front offices and managers. More analysis should be conducted to confirm and expand on the findings of this project. However, this case study can be used as a foundation for a new and innovative approach to player evaluation, ultimately complementing existing methods and informing decisions regarding otherwise intangible factors.