System engineering (SE) is a structured systematized methodology that deals with designing, managing, and optimizing systems performance. System engineers use the perspective of system thinking to make the successful use and retirement of engineering systems. Since the role of system engineers ranges widely from technical support to customer interaction, system design to management, there is a demand to develop a cadre of effective systems engineers. However, two critical questions are not well-defined in the extant body of SE literature: (1) What are the fundamental attributes of systems engineering that would influence the performance/effectiveness of individual systems engineer? (2) What are the corresponding leading indicators for appraising the performance of an individual systems engineer? To respond to these questions, this study proposes a new instrument to evaluate the system engineers' performance and subsequently identify their strengths and weaknesses within the complex system domain. The instrument is based on the set of performance indicators examining six fundamental system engineering attributes. The implication of this study would assist systems engineers in strengthening their system skills and reflects a state that can be improved through training, workshops, and education to prepare them to face the complex situations originating from the problem domain.