I always think when a player has a very weak second serve Ala Radwanska to hit just two first serves, if she hits 15 double faults i would mind. But if I say that to Errani her first and second serve are no different.
The facts that she served 97% and broken 3 times and only won 57 percent of those 97% says a lot about her serve. It's a spin serve in the middle of the box. And barely do you find players that hits a spin serve in the middle of the box, if she misses that serve that is embarrassing.