Sphere Factor
A football is not, it would seem, just a football. Every league and major tournament has its own ball. The 2010 World Cup, for example introduced the Jabulani, a revolutionary Adidas design said to fly truer than any other ball. However, with every new ball comes a new raft of complaints about how it plays. Speaking on Radio 5 back in the spring, England Goalkeeper David James said that the Jabulani would cause keepers a lot of embarrassment. Conversely, strikers complained that it was difficult to keep down, at least English strikers did! How can different footballs, which by the way, have to conform to a regulation size and weight, contain so many surprises? The three factors most likely to affect play are how well the ball keeps its shape, the degree to which the slight weight in-balance caused by the inflation valve is minimized and lastly, visibility. It is likely that commercial imperatives, rather than the pursuit of dynamic perfection drive the introduction of new and excl...