Kinetic data for structural relaxation in silver iodomolybdates at the glass transition temperature (T-g) are obtained by high-pressure differential scanning calorimetry (HP-DSC) and are compared with activation energies (E-A) and volumes (V-A) obtained earlier from conductivities below T-g. The results are fitted to an empirical equation, E-A = MVA, and displayed in the form of a master plot of E-A versus V-A, an approach previously applied to strongly coupled systems, including polymer electrolytes and molten salts above their glass transition temperatures. The parameter M emerges as a localized modulus, expressive of interatomic forces within the medium, linking together E-A,E-sigma, V-A,V-sigma and E-A,E-s, V-A,V-s, the "apparent" activation parameters for ionic conductivity and structural relaxation, respectively. The V-A and E-A values for ion transport are much smaller than the corresponding values for structural relaxation. However, remarkably close agreement emerges between the "process parameters", M-s and M-sigma both close to 8 GPa, thus establishing a quantitative link between ion transport and structural relaxation in this highly decoupled system. A new E-A versus V-A master plot is constructed, which points the way to a unified approach to ion transport in polymers and glasses.