A method is provided for analyzing and diagnosing a large scale process automation control system having a plurality of control loops. Assessments for pre-defined key performance indicators (KPIs) are automatically generated for control, process and signal sections of each control loop. The automatically generated assessments of the pre-defined KPIs may be displayed in a graphical user interface (GUI) of a computer. A user may change the automatically generated assessments of the pre-defined KPIs. Different data views may also be displayed in the GUI. The data views include time series trends for measured process variable, controller output, controller set point and error, as well as controller parameter clustering views in two-dimensional and three-dimensional plots.