The Wall Between Knowledge and Agency: From Operationalized Self-Research to Individual Agency under Pressure in High-Performance Tennis

High-performance tennis creates a developmental environment spanning many years in which performance, ranking, tournament access, repeated competitive experiences, and increasing pressure are closely interconnected. At the same time, modern high-performance systems have access to ever more data and knowledge about athletes. Yet it does not automatically follow that this knowledge becomes a capacity for action within the individual athlete that is available under pressure. This paper refers to this developmental distance as The Wall Between Knowledge and Agency. Building on the concept of Operationalized Self-Research, this paper examines how population-level knowledge might first be transformed into person-specific, longitudinally revisable knowledge and, beyond that, into person-specific learning, regulatory capability, and Individual Agency under Pressure. Agency is not understood as complete control. It refers to an increasing capacity to perceive relevant intrapersonal processes, understand them in a person-specific way, develop and select regulatory options, decide and act under pressure, learn from consequences, and recognize when professional expertise is required. Even high levels of agency guarantee neither successful regulation nor athletic performance, but may increase the probability of situation-appropriate action. High-performance tennis serves not merely as an application example, but as a specific developmental system in which person-specific learning must be built over long periods and under changing conditions. The paper argues that knowledge alone does not produce regulatory capability, that capabilities available under controlled conditions are not automatically available under high competitive pressure, and that repeated experience cannot be equated with learning. As a possible future infrastructure, the paper develops a longitudinal Athlete–Human–Machine architecture. The athlete remains the locus of experience, learning, decision, and action. Human expertise assumes professional judgment, pedagogy, intervention, training design, and responsibility. Technical systems can support long-term continuity, information processing, comparison, retrieval, the identification of information gaps, and person-specific hypothesis testing. This architecture does not describe an already validated system, but formulates a conceptual research agenda. From this argument, testable propositions are derived for person-specific learning, regulatory development, Agency under Pressure, and the potential scaling of longitudinal developmental work in talent development. The paper's central shift in perspective thus moves from knowledge about the athlete to person-specific knowledge for the athlete and ultimately to a capability developed within the athlete to increasingly perceive, regulate, decide, act, and continue learning independently under pressure. About the athlete → for the athlete → within the athlete