Social media and discussion centric collaborative tools have become an integral part of software development team communication. Accessible by mobile apps and alongside development tools, these tools provide a medium for conversation and enable teams to share project artifacts including commits, documents, and models. As with other forms of human communication, team members naturally emote during software development, resulting in affective post content expressing emotions such as urgency, frustration, and commendation. The effects of affective interaction on team performance, while studied in the literature, are still not well understood, particularly for student teams. This paper adds to the exploration of affect, by examining the effect of emotional post content on project performance metrics among teams of students in a software engineering course. The data set consists of over thirteen hundred forum posts produced by five teams across three Scrum Sprints in two different classes, each of which was taught by a different instructor. Using manual sentiment analysis techniques, we found that individuals with less emotive posts performed better than those that emoted more and that less affective individuals were evaluated more positively by their peers. From a pedagogical and management perspective, these results indicate that intervention may be needed when posts become emotionally charged in software development team communication.