Czuch Chuckers:
- It is possible for a player to loose most of his games against great players and so have a BKR better than a player who wins most of his games against weaker players
- It is possible for a player to make lots of multi-jumps on froglet and still have less moves per day than a player who had lots of forced moves on checkers and needed only half the clicks to get there
- it is possible for a player to throw only double-6 at backgamon and still loose the game
- it is possible for the candidate for president in the USA and other electoral systems to have less votes and still be elected
- ...
- it is possible for a player to have fairly good BKR at most of his 40 ranked game types and still not make it to the list of a player of only plays 11 totally different game types

No matter what you do to make a system fair, there will still be the possibility to skew the results. If you go through that list of top players, you'll find out most of them have games from fairly different types. Different game types have different weights here - and if you consider chess I'd say there's at least 5 or 6 of them. Some games have more variants than others and some just are more biased than others. And no matter what you say, no two games are really alike.
I think the current list is just fine. It will be biased no matter how you rank it... Now, what I'd really like to know would be the average BKR of the player that is ranked in ALL game types. But I guess this list would just go blank whenever a new game type is introduced in BK... which on the other hand, would make the competition to be in that list really interesting :)

P.S: (please read "his or hers games" in all of the above . Girls are good players as well as boys)