Hello Halifaxtiger, I agree this rule appears to be unclearly written. However, surely the key word is 'latest'?
Is the highlighting of the second sentence your own? If so then, without highlights, it reads as if the second sentence would apply only if the rider held averages from both leagues in the same season. It would appear to make more sense that way. As a hypothetical example, a rider might have been at the peak of his form in a Premier league side in 2011 but over the course of 5 years (a long time in a rider's career?) picked up injuries, got older (!), semi-retired to a NL side and performed less well. Why then should his earlier average apply if he is no longer the rider he was? (Casting no aspersions on Adam Roynon of course )
John