LionsLair: One of the reasons is that BrainKing keeps a history of all past games - so when you start to delete players from the database, their games that are attached to those games start to mis-match and such.

Which I'm sure there are ways to get around it and such, but the much simpler solution is just not delete them.

In the players list, you can sort by the last action to easly see how many "active" players are still on the site and such if you are looking for those typs of stats.