Edge plasma parameters influence plasma performance in many different ways (profile stiffness is probably one of the best known examples). In ELMy H-mode, a thin region with improved transport characteristics (Edge Transport Barrier) links the core and the scrape-off layer. There is a strong coupling between these three areas, so that even a modest variation of plasma parameters in one region can lead to a dramatic change in the overall plasma performance. Systematic MHD stability analysis and self-consistent integrated predictive modelling of a series of JET ELMy H-mode plasmas, including scans in gas fuelling and triangularity are presented.