I'm not so sure it's fair to pick on the Williams sisters. After all it isn't conclusive that they are baptized witnesses themselves. I understood that it was their Grandmother that's the witness and perhaps the mom. Venus did thank "her" God Jehovah after a match once, but any kid raised around a zealous witness might do that.
I've seen Dad smoking a cigarette during a match and the girls have waved a flag on more than on occasion. So, my guess is they are not witnesses.
They seem to be very upbeat and always give a smile for the camera. I wouldn't dog them too hard. And Serena is done at the Australian Open already.
Never Squat With Yer Spurs On