The Internet has not only revolutionized our ways of communication but has also expanded firm's potential sources of innovation. Dahlander and Wallin (2006) have shown that firms deploy their personnel, the so-called man on the inside (MOI), to participate in open source communities in order to unlock the valuable assets that are voluntarily being created in these communities. Focusing on firm-sponsored open source communities, we will detect the functions of MOI and how these individuals influence the community by applying a comparative case study of two open source software firms, which includes interviews with managers and MOI, netnographic and social network analysis of the community interactions of over 12,000 individuals. We conclude that despite the fiery situation of combining open source philosophy with a firm's profit-driven business model, firms can succeed in integrating a community into the firm's development process with the help of the MOI. These key individuals carry out five core capabilities that are crucial to become central nodes in the communication networks.