Which still wouldn't explain why Nadal has the least number of votes in the four, unless you're attempting to suggest that Nadal fans are somehow less likely to vote.
Something to behold indeed.
Are you actually suggesting that Nadal is less popular worldwide than Murray and Djokovic?
I would find that quite hard to imagine. Facebook seems more reliable for such a popularity contest as opposed to an ATP site with a poll that I never even looked at though I check the ATP site regularly unlike most people who like tennis (who never even go to that site in the first place). Nadal wasn't playing the last 6 months and his fans are probably less likely to be all over the ATP site and looking to "vote" for him online but who knows really...
Nadal is hated much more on English language tennis boards than others for a variety of reasons which I am not interested in debating with the usual MTF board follower but such boards are hardly representative of the much, much larger world of people who would say they enjoy tennis.