eSports is a rapidly growing phenomenon in competitive gaming. Expertise is an interesting topic to study in relation to eSports, as eSports athletes are considered among the most highly-skilled players of their particular games. Examining expertise not only advances the understanding of what skills compose professional play but enables a deeper study of learning in games; before learning processes are studied, it is important to detail what learning these processes should produce. This study examines expertise through the application of thematic analysis to a series of interviews with professional players of the eSports game, Overwatch. The goal of this study is to identify which skills are perceived to be important to professional-level play by professional players. Two overarching themes were identified, game sense and mechanics. A number of sub-themes were identified as important, including survival, anticipation / prediction, communication, thoughtfulness, aim, ability usage, movement and positioning, and team-based mechanical synergies.