Did you see that final? Mirnyi was absolutely useless, paralyzed by nerves and he kept feeding Bryan easy volleys with his BH return. Robson played a very good first set but became equally useless after that. So basically it was Murray vs Azarenka, and Vika won believe it or not.
Someone who is in between... so you can't really say they are one or the other but have both qualities. But realistically I don't think people are completely one or the other. Most people are probably ambivert, more or less.