Bulk metallic glasses (BMGs) possess a number of important mechanical properties, such as enhanced ductility, which stem from the fact that they are structurally disordered in contrast to crystalline metals. Materials scientists have identified several features that are highly correlated with the glass-forming ability of metallic glasses. For example, good bulk metallic glass formers are typically multi-component alloys composed of elements with atomic radii that differ by more than 10%. In addition, most BMGs possess a negative heat of mixing, which disfavors clustering of like atoms. In this work, we investigate the relative contributions of geometric frustration (polydispersity in the atomic radii) and energetic frustration (polydispersity in the cohesive energies of different atomic species) in determining the glass-forming ability of binary alloys. We carry out molecular dynamics simulations of binary alloys with no geometric frustration, but with tunable energetic frustration. The atoms interact via Lennard-Jones-like potentials with attractive well-depths that are tuned over the range found in experimentally observed metal alloys. We find that metallic alloys with monosized components can be good bulk metallic glass formers provided the energy parameter that controls mixing is much larger than the cohessive energy of the atomic species.