A milestone in the mathematical modeling of complex systems is the analysis of the significance of the system components. When examining the reliability, Birnbaum (1968) proposed measures of element significance. This direction of research into mathematical models of systems has led to many alternative analyzes. The aim of the article is to further expand the diagnostic capabilities of systems through a specialized analysis of their mathematical models. We propose, using the methods of game theory and stochastic processes, functionals that measure the structural reliability of the system and the operational performance related to maintenance. This allows for the construction of a new measure of significance, using knowledge of system design, reliability, and wear to optimize repair and maintenance. The considerations of this work are aimed at showing the ways of applying this approach to multi-state systems.