Hmm,I think the criteria to qualify for Bali is be one of the 10 highest ranked players that have won at least one International tournament during the year and are not participating in the WTA year end Championships.
Zvonareva technically has qualified for Bali,but I'm not sure if she'll be playing in Bali because she'll be in Doha as an alternate. Pennetta has also qualified but she stated she will not be playing due to her participation in the Fed Cup.
Yeah,I feel it should consist of players ranked after the top 8 who have qualified for Doha,but I guess the criteria is to give more opportunities to players not so highly ranked,yet have worked hard this year to win more prize money than ever,so in a way it seems fair and nice to reward less known players for their efforts.
So far,players who have qualified for Bali include Zvonareva,Bartoli,Stosur,
Wickmayer,Medina Garrigues,Martinez Sanchez,Pe'er,Czink,Szavay and Rezai.