No it isnt. I am not saying the person who is considered the best is always Serena, but it is almost never the year end #1. Lets look over the last 15 years: 1998- Davenport year end #1, Hingis best player and best record. 1999- Hingis year end #1, Davenport best player and best record. 2000- Hingis year end #1, Davenport year end #2, Venus year end #3. Venus though Worlds best player, Davenport second best, Hingis third best. 2001- Davenport year end #1, Capriati year end #2, Hingis year end #3 but #1 ranked most of the year, Davenport year end #4. Venus though Worlds best player by far, Capriati second best by far, Serena probably third best, Davenport fourth best, Hingis about 9th best. 2002- Serena year end #1, Serena best player 2003- Henin year end #1, Clijsters year end #2, Serena year end #3. Serena clearly best player but the rankings were skewed by injury so ok. 2004- Davenport year end #1, Henin year end #7. Henin years best player, Sharapova (who ended ranked #5 on computer) 2nd best player, Davenport about 7th best player. 2005- Davenport year end #1, Clijsters years best player, Davenport again probably not even top 5. 2006- Henin year end #1, Sharapova year end #2, Mauresmo year end #3. Mauresmo years best player and Henin second best. 2007- Henin year end #1, Henin best player 2008- Jankovic year end #1, Serena best player of year 2009- Serena year end #1, Safina very close #2 and #1 ranked most of the year. Serena by FAR years best player, Venus or Kuznetsova 2nd and 3rd best, Kuznetsova 4th best, Safina something like 8th best. 2010- Wozniacki year end #1, Clijsters best player of year (note if I was only looking at major wins and nothing else I would have said Serena). 2011- Woziacki year end #1, Kvitova year end #2. Kvitova by FAR best player in the World for year 2011, Wozniacki about 5th or 6th best. So in 2 years the Worlds best player was year end #1, 3 if you add 2003 which was correct based on results atleast. Sometimes someone who is only about the 7th best player in the World is year end #1. WTA rankings = meaningless to determine greatness. Next. As for your question to who was the best player while Wozniacki was ranked #1 well sure as hell was never her, that is for sure. Most of 2010 it was Serena, late 2010 and early 2011 it was Clijsters, and by the end of 2011 it was clearly Kvitova even with her bad 2 month patch in the summer (most of Wozniacki's year was a bad patch, well for any top players standards other than her own meanial ones that is). Her 2011 year end #1 is the biggest joke in history, and no this doesnt even involve Serena since I concede Serena has no case whatsoever for the 2011 #1 ranking. Kvitova, who I am not even a fan of either btw, won more tournaments, won bigger tournaments in stronger fields, won a slam, won the WTA Championships, had better slam results, won tournaments on all surfaces, even had a better W-L % which proves the stupid consistency argument for Wozniacki is even BS. Wozniacki was not at all consistent in 2011, after April or so she was crap the rest of the year, losing early rounds to much lower ranked players at most events she entered. There is no better evidence of the ridiculousness of giving merit to WTA rankings than the year 2011. Now as for 2012 atleast one could make a case Azarenka deserves the #1 ranking based on consistent performance (unlike Fraudniacki in 2011), but as anyone with a brain knows even if she does perhaps deserve to be ranked #1, nobody considers her the Worlds best player, nobody considers her to have had the best or greatest year, nobody would rather her 2012 results than Serena's, and thus even if deserving of the #1 ranking she still proves the meanginless to the #1 ranking stat in womens tennis to whom should be considered better or greater in any scheme or context.