The Indie 500, although no longer the storied event it once was, is certinly not a fairly minor car race. That being said, Patrick has yet to win a race in the big leagues and I suspect her star is going to fade fairly quickly if she does not start winning.
I would also think that Michelle Wei has moved up in those rankings, probably to second place right now. She too has yet to win a tournament in the big leagues, but the thing is, unless the world spins out of its orbit, she no doubt will win a big one, while Patrick could easily not win anything of importance.
And Maria will stay up there for awhile, although he star will begin to diminish if she doesn't win a major in 2006.
But I also question what "Most Powerful" actually means in all these cases. None of the athletes are exactly in control of the sports they play. And, as we have seen in tennis, life goes on with or without the stars. Both Williams sisters are gone for significant periods of time and the sport does not slip into crisis mode.
The same thing obviously proved true about Hingis. She left and life went on without her, although her impending return has generated a lot of buzz because the sport has not, with the exception of Maria, found another super star.
But the economics of the sport seems to operate somewhat independently of the appearance of any stars. Maria won the year end championship in 2004, but that wasn't good enough to make the Staples Center event financially profitable and it will be in Spain next year.
Maria may be able to move cell phones or watches or perfume and the Willies may be able to sell hamburgers, but none of them can guarantee financial success in the long run for any tournament.