Today's successful IT service providers need to continuously improve the transparency of their service provision. The selection and negotiation of key performance indicators is an important component in establishing transparency. In this workshop contribution we aim at characterizing the role of key performance indicators in management system, in general, and IT service management systems, in particular. We discuss the theoretical background of process-oriented quality management systems, i.e., the management school of cybernetic feedback-control systems. We express our opinion that a purely mechanical application of quality management systems comes at the risk of misunderstanding or overlooking important parts of the functioning of a successful enterprise. Against the background of these findings we can understand mainstream IT governance and IT service management systems as process-oriented quality management systems. As part of the discussion, we reconsider the mainstream IT planning instruments of total cost of ownership and total economic impact and extend them by a means to incorporate probabilistic risk assessment.