As the electricity market undergoes continuous evolutions, along with the widely-recognized outdated nature of the grid, system operators would have to be able to more effectively manage the system operation expenses since waves of maintenance costs and equipment investments would be anticipated in a few years to come. Strategic implementation of cost-effective reliability-centered maintenance (RCM) approaches seems to be a key solution. This paper proposes an efficient method to assess the component criticality for system overall reliability and further maintenance focuses. A solution concept of game theory, called shapely value, is proposed that is able to fairly identify the contribution of every single equipment's to the system reliability performance once a high-order contingency occurs under different loading conditions. The identified critical components are then systematically involved in a new optimization framework for effective scheduling of RCM implementation in power systems. The suggested framework helps in realizing where investments and maintenance to be made in the grid to ensure a desirable system reliability performance. Implemented on the IEEE reliability test system, the effectiveness of the suggested framework is confirmed by comparing to conventional techniques under various scenarios.