Not qualifying for RG was an accident for Petkovic who even fancied retirement from tennis after that loss, but who after that did pretty well and reached 2 finals. Alexandra reached 3 main draws and she lost in the first round in two of them. I think the comparison between AP & AD is not the best one at this moment.
But yeah, I deeply wish her all the best in the future tournaments! Who knows? Maybe losing today 1&2 with Arvidsson is a good sign that she'll reach the semifinals of the US Open