One season (08-09) does not a rivalry make.
It's a bit of a stretch to count the 09-10 season as Mao and Joannie have only met head-to-head once (Olympics), Japan Open was a glorified cheesefest. Maybe if Joannie continues her competitive skating career there may be a rivalry, but that doesn't seem likely at this moment. Besides, Joannie's competitive record pales in comparison to Mao--Mao is 2x World Champion, 2x 4CC champion, and 2x GPF champion while Joannie hasn't won a single ISU championship. Miki is closer to a rival to Joannie than Mao, but even Miki has a world title under her belt.
Imo Joannie used to be ridged and tight but she really has found herself and I find her a joy to watch. Her new SOI exhibition is wonderful. And also imo Mao seemed to try to hard for me to really get into her programs for the past seasons. At the Olympic short she really came to life for me and then again at the 2010 Worlds she seemed closer to her pre 2008-2009 season self. Mao still has a awesome looking 3-3 even if it probably wouldn't get ratified.
Since Miki won the bronze at the 2009 worlds and finished 4th this season I think we shouldn't write her out of the picture yet. If she hits her jumps she's still a threat. I''ve never been a fan of her skating though I loved her 2006 programs.
Yu Na is a consistent and lovely skater who has come a long at the right time in history for her to truly dominate. If she can stay healthy she should be strong for years to come even if she doesn't improve her limited weaknesses. I think Mao and Mirai can get close to her if they hit their jumps good enough to get ratified and has good programs. I think Yu Na really had great programs this season and I loved her short nearly every season so I hope she stays around. I hope Joannie retires and pushes for more North American pro events and I hope Mao remembers to enjoy herself instead of trying too hard to be great. I hope Mirai skates like she did at nationals and the Olympics with slightly more rotated jumps then she can be a real contender.
Mao has topped Joannie 6 times out of 9 (2010 Olympics, 2007 and 2008 Worlds, 2008 4CC, 2008 GPF, 2007 Skate Canada) while Joannie has beat Mao 3 times all in the same season (2009 Worlds, 2009 4CC, 2008 TEB). If Joannie continues beating Mao, I'll be more convinced that they have a real rivalry.
Also, isn't it funny how statistics produce very different results when you adjust the size of the sample?
Tara and Michelle both competed on the senior circuit from 1995-1998, so it would be reasonable to only count Michelle's titles in the years that they were actually competing against each other (just as I had only compared Joannie and Mao starting from the 2006-2007 season). If we were to count number of ISU championships won during that timespan, Tara had 1 Olympic title, 1 world title and 1 Champion Series Final title to Michelle's 2 world titles and 1 Champion Series Final title (though Michelle's 1998 world title was won during Tara's absence). Those are very comparable records, especially given that Tara was virtually a nobody during the 95-96 season. True, Tara only really dominated Michelle for the 96-97 season, but Tara did also manage to win the biggest title of the 97-98 season in the midst of Michelle's dominance and moreover, Tara was only on the full senior competition circuit for two seasons.