For sure the methodology is flawed, endorsement dollars and google searches are going to skew the results massively towards richer countries.  But famous implies the number of people that know of a given athlete, and so some sort of number crunch is required.  ESPN probably ran a bunch of different scenarios and looked at the different lists to see which one passed the smell test and would generate clicks in their home market.  Thus they needed a soccer player at #1 for credibility, and a load of American athletes to make some sales.