Your scores have a large bias towards players with many posts as you don't control for the number of posts the target player has made.
A more correct way to find fans would go something like:
(number of upvotes A gave B)/(number of posts A saw of B)
[Spoiler]posts seen isn't the total count of posts, as not everyone are the same time on this forum. A good estimation would be the count of posts made by player B after the first upvote/downvote by player A
You may need to remove some false positives (someone with a single post that at least one person upvoted)