Raising your game at a slam
Watching the late career arc of Schiavone, I wondered how is it that she really hasn't done anything all year on the regular tour, but has played well in the 3 slams. So has Li the last couple of years. Of course Serena and Kim. But why do others struggle? I think of Sveta, who squeaked by Zhang, as well as some of her other slam matches against Akgul, Mathilde and other lower ranked players. Ivanovic goes without saying.
All of the above mentioned won slams. So there is a different category for those who don't give you confidence even when they are doing good, like Peer, Stosur and Azarenka, yet we have confidence that Dulko, Duchevina and Bartoli will always pull off one upset.