To address variability in manufactured cell therapies, we conducted deep characterization of isolated PBMCs and correlated these profiles with the expandability and potency of processed Gamma Delta T cells (TCRγδ+). PBMCs were first evaluated for metabolic fitness and polyfunctionality—the breadth and robustness of cytokine release—and rank ordered accordingly. Following a 14-day expansion, TCRγδ+ cell growth, viability, and potency were assessed. Results showed that high metabolic fitness and polyfunctionality produced greater yields and enhanced potency. These findings underscore the importance of carefully selecting starting material to optimize therapeutic efficacy and overcome barriers to clinical adoption of cell-based therapies.