The performance of robust controllers hinges on the underlying model set. However, at present it is unclear which properties of the physical system should be accurately identified to enable high performance robust control. The aim of this paper is to clarify the intimate relation between quality of certain physical system properties and the resulting control performance. Hereto, an extended robust-control-relevant system identification methodology and a new visualisation approach is developed that is applicable to multivariable systems. The developed methodology is applied to an industrial wafer stage system. Experimental results indeed confirm that the developed techniques contribute to clarifying the complex relation between system identification and robust control.