In this study, we propose a link between L2 rhetorical concepts and ELF as a way of the analysis of the development of a single concept, of an EFL college student's rhetorical knowledge. Using Vygotskian sociocultural theory as analytical lenses, we examine whether L2 rhetoric can be mastered and internalized as a culturally neutral concept, i.e., the formulaic knowledge of L2 writing the student has learned from the NEST through instruction; and how the student's L1 rhetorical concept and ELF performance together mediate his L2 concept development in his academic writing. The data consist of a student's personal narratives, text-based interviews and academic writings. Rather than the mastery of a single variety of English, he produced texts that reflect the flexibility and variability inherent in written ELF. From ELF perspectives, this study offers an opportunity of establishing a new normal, in which rhetorical conventions of texts should be viewed as constructs that are dynamic, emergent, and therefore negotiable and adaptable.