In this paper we argue that the choice of research methods reflects the theoretical framework even before these methods have been put to use in case studies. We understand the term 'case study' broadly in this paper and argue that neither thinking of them as cherry-picked cases to support preconceived ideas about mathematical practices nor thinking of them as inductive leaps from (too) few cases to general features is suitable. By realising the deep entanglement of our case studies with our theoretical framework we propose to view case studies as an invitation for critical reflection upon one's own assumptions. We discuss an example taken from the philosophy of mathematical practices. The upshot is threefold: (1) we provide an argument that case study based research strategies can be successful; (2) we delineate how an awareness of the methodological difficulties of case study based research strategies can positively influence the way case studies are conducted; (3) we suggest that case studies are not dispassionate examinations that deliver cold facts.