Identifying structure-performance relationships is critical for the discovery and optimization of heterogeneous catalysts. Recent theoretical contributions have led to the development of cl-band theory, which relates the calculated electronic structure of a metal to its chemical and catalytic activity. While there are many contributions where quantum-chemical calculations have been utilized to validate the cl-band theory, experimental examples relating the electronic structures of commercially relevant nonmodel catalysts to their performance are lacking. We show that even small changes in the near-Fermi-level electronic structures of, nonmodel supported catalysts, induced by the formation of surface alloys, can be measured and related to the chemical and catalytic performance of these materials. We demonstrate that critical shifts in the cl-band center in alloys are related to the formation of new electronic states in response to alloying rather than to charge redistribution among constitutive alloy elements, i.e., the number of d holes and d electrons localized on the constitutive alloy elements is constant. On the basis of the presented results, we provide a simple, physically transparent framework for predicting shifts in the cl-band center in response to alloying and relating these shifts to the chemical characteristics of the alloys.