Massive Open Online Courses (MOOCs) are frequently portrayed as "agents of change" in higher education (HE), impacting on institutional practices, processes and structures throughout HE. However, these courses do not "fit" neatly with the established aims and functions of universities, and accounts of technology-led change in universities predominate, simplistically emphasising technologically determinist narratives with incidental social effects. This study aims to explore the consequences of introducing these courses into HE in terms of the roles of educators, learning designers and the socio-technical construction of MOOCs. The research takes a socio-technical perspective, combining the established analytical strategy of Socio-Technical Interaction Networks (STIN) with the social theoretical "third space" framework of HE activity. The paper reports on the first of three institutional cases studies, finding that learning designers occupy a hub-like position in the networks of actors involved in MOOC development within an emergent "third space" between academic and managerial roles. The analysis also reveals how the massive and open elements of these courses elicit involvement of seemingly peripheral actors, who exert a strong influence on course production processes and content, with educators taking a less central role. This work adds a socio-technical element to understandings of third space activity in higher education, and can inform the planning and development of online education projects in accounting for changing roles in HE where massiveness and openness are combined in a course.