The turbulent reacting flow in an industrial gas turbine combustor operating at 3 bar is computed using the large-eddy simulation paradigm. The subgrid-scale combustion is modeled using a collection of unstrained premixed flamelets including mixture stratification. The nonpremixed combustion mode is also included using a simple closure involving the scalar dissipation rate of the mixture fraction. Close attention is paid to maintain physical consistencies among subclosure models for combustion, and these consistencies are discussed on a physical basis. The importance of the nonpremixed mode and subgrid-scale mixture fraction fluctuations are investigated systematically. The results show that the subgrid-scale mixture fraction variance plays an important role and comparisons to measurements improve when contributions from the premixed and nonpremixed modes are included. These numerical results and observations are discussed on a physical basis along with potential avenues for further improvements.