Authentically representing biologically driven processes in Earth system models remains a significant challenge, and the need to revisit long held assumptions about processes governing soil biogeochemical dynamics is acute. A growing chorus from the biogeochemistry, soil science, and ecosystem modeling communities calls for model structures that provide direct microbial control over soil C dynamics. I will describe a new model that explicitly represents microbial physiology in its representation of soil C cycling on the global scale. This kind of microbial explicit model can simulate global soil C pools that more closely match contemporary observations but generates wildly divergent results in response to environmental perturbations. The discrepancy between projections in non-steady state simulations highlight the modeling processes, parameters, and structures that deserve greater attention from both empirical and modeling communities and provide avenues to begin exploring soil biogeochemical theory across spatial and temporal scales.