A competitive arena, as opposed to an industry, is used as a primary lens through which to understand the world and therefore what the effects of a potential inflection point might be. Think of an arena as a definition of the setting where customer need connects with company solution to create value. An arena can be seen as super sized and strategic use cases that enable an organization to concentrate on what is really going on. It provides a tool with sufficient scope for meaningful change without falling into strategic paralysis. This is one idea that make the book worth the read.