Open innovation (OI) has become an established business practice followed by many organizations and industries. This paper extends understanding about how middle managers work with performance indicators to strategize OI by taking a bottom-up perspective in the organization. It draws on interviews carried out with eighteen (upper-level) middle managers from different global and internationally recognised organizations. Through an abductive study, we compare how these middle managers reason about their work with performance indicators to mobilise top managers towards an OI strategy. Findings show that the situational nuances middle managers find themselves in, such as the extent of strategic support for an OI strategy by top managers and the degree to which OI practices are adopted, plays a critical role in influencing how they work with performance indicators. According to these situational nuances, we distinguish different OI contexts which affect how middle managers reason about their work with performance indicators. We label the different types of reasoning as abstaining, initiating, expanding, restructuring, and retaining.