Okay so we all know about the butterfly effect: How, in a system as complex as the historical process, small changes in one place can result in large and unpredictable changes in other parts of the system further down the line. And that it can be a useful way of summarising the small changes that ripple out from a divergence, and should be used as an excuse for including various scenarios in the timeline.
I think this is complete crap. When someone creates a fictional world to serve as an element in a story, he is constrained by the other elements of the story, and, unless restraining himself, free to modify the course of history to fit with those elements. He can use any number of divergences, and set their outcomes to whatever works best for the story. If a few unlikely accidents and coincidences are needed to create cows landing on Mars, or whatever, so be it.
Trying to use the butterfly effect in an argument is completely pointless.
Firstly, realism. We have no way of knowing what a real alternate history would look like, and the task is too complex for any realistic simulation, even if we had enough data. Consider the weather. If a butterfly flapping its wings can cause a hurricane, then what impact would the differing movements of hundreds or thousands of people have? Consider the vast number of people born each year, with various talents and abilities that are highly dependent on the circumstances of their conception. Given how altering the destiny of one or two men can change the course of history, how can you hope to alter that of thousands without making the world quickly and unpredictably unrecognisable?
The answer is that you don't. Looking at alternative histories is a fundamentally fantastical exercise. Its goal is to either amuse or instruct. With the first, you can do more or less what you want, provided you create the intended effect. With the second, you need to restrict yourself to working out the logical implications of the divergence, with a certain fudge factor to account for your own areas of ignorance, while making the assumption that all else is equal.
Which brings us on to possibility. Using the butterfly effect as a means of expanding the range of possible outcomes is equivalent to saying anything can happen. Absolutely anything. It means that you have abandoned the constraints of causality, and so cannot say anything about the underlying mechanisms of history.
Ball 1 was always going to be Wigan or Everton. It was pulled out alongside Ball 4. They are the only two facts that are necessary here.
