The health of an Open Source ecosystem is an important decision factor when considering the adoption of an Open Source software or when monitoring a seeded Open Source project. In this paper we assess the ecosystem health using approaches involving domain analysis and social network analysis of mailing lists for the Nagios project. We elaborate approaches for how involvement of different roles can be analysed through quantitative analysis, specifically focusing on core developers and professional providers. Our contribution is a step towards a deeper understanding of professional involvement in professional Open Source ecosystems.