Candace Parker is the best big woman in the WNBA. She's 6'3''. She's slower than Eddy Curry, she can't jump as much as Brian Cardinal, she can't change directions as quick as Adonal Foyle, she has less strength than Luke Ridnour and she doesn't handle the ball better than DJ Mbenga. She'd would have to play as an undersized SG in the NBA.
Now Diana Taurasi is a freak - even more of a freak than LeBron James, IMO. I can perfectly see her being a decent rotational player in some minor NCAA college. She would never be drafted to the NBA and her chances of having a professional career overseas would be extremely small though. Maybe in very small, semi-pro, leagues. But I think it's more enjoyable to appreciate her amazing combination of skill, athleticism, mental toughness and physical prowess while she's around than to speculate about this.