Athlete brands exist within a network of brand relationships. Thus, considering the joint influences of related brands at different levels (league, team, and athlete) is essential for understanding how athlete brands are built. We focus on growth factors impacting athletes’ social media followings (Twitter and Instagram) around the critical juncture of team transfer periods. We use data from the NFL Draft, because this moment in time provides a key opportunity to capture combined influences from league-, team-, athlete-, and platform-related factors on athlete brand development. Through comparing a large sample of athlete social media followings before and after the draft, we identify immediate changes as athletes start their professional careers. Results indicate examining multiple factors in the same model is essential for understanding the role each plays in building athlete brands. The league and team represent master brands into which an athlete brand is integrated, and consequently athlete brands are provided with benefits from these new brand relationships. Results further demonstrate network effects, highlighting the importance of possessing a strong brand before a high-profile event.