Cibulkova plays a high risk style of tennis, so to me it's not surprising to see her have big results here or there and then nothing during several months. When it clicks, she's amazing, but everything has to be in place, mentally, physically and technically, otherwise things become complicated for her.
That, added to the fact that her height reduces a great deal the security of her shots, starting with her serve. She can't rely on her serve to go through the matches in which she's not playing well (like a lot of the female pros by the way, which in part explains the more erratic results in WTA), so she always has to go for aggressive and risky shots to make a difference, like against Azarenka last night.
We never know, but I doubt she'll ever have great results during a whole season. And that's not necessarily a bad thing, that's all the more impressive when she's playing like she has during this AO.