The energy consumed by communication networks can be reduced in several ways. A promising technique consists in concentrating the workload of an infrastructure on a reduced set of devices, while switching off the others. This technique, , called “resource consolidation”, is particularly appealing when routing data traffic over a lightly loaded network. However, deciding on the set of routers that can be safely switched off requires an accurate evaluation of their criticality in the network. In this work, we define a measure of criticality that does not only take into account the network topology, but also the traffic matrix. Employing a game theoretic approach, we model the scenario as a coalitional game, and show the effectiveness of the Shapley value as a criticality index. Shapley value ranking is used to drive the resource consolidation procedure, and is compared with other classical indexes on a real network scenario. Numerical results confirm that the proposed index provides a robust and relevant criticality measure, yielding a good tradeoff between energy efficiency and network robustness.