This study investigates the development, implementation, and establishment of evaluation metrics within the mathematics research community in Chile, a discipline where the use of bibliometric indicators for quality assessment has been highly controversial. Using a mixed-methods approach, the study conducted focus groups with mathematicians at different stages of their academic careers and analyzed the ANID Mathematics Studies Group's method for assessing researcher productivity. The findings reveal that the evaluation metrics in mathematics remain in a state of “magmatic flow,” fluid and solid, constantly changing yet stable enough to articulate multiple social worlds. The study highlights the challenges faced in three closely linked spheres: mathematical research, science and higher education governance, and organizational management. The functioning of this metrics assemblage as boundary infrastructure, which meets the information needs of diverse social worlds while maintaining the integrity of the interests involved, is a temporal achievement of situated practices that provide continuous adjustment and stabilization. The study suggests that academic metric assemblages are made unstable through practical politics involving controversies and qualitative deliberation. Concurrently, they achieve stability through translation and blackboxing practices.