She is just too slow. Just not agile enough. She doesn't just struggle chasing on the counter. She struggles to stay in front of people. I think that the second we get a strong alternative (like Jorgensen), we never see Rustand on the back line again. That is assuming we do get such a replacement, but odds are good.
Like you mentioned though, I could see Rustand do well in the midfield. She has great touch, sees the field extremely well, and can pick out a really good pass (last night's awful mistake notwithstanding). She would have someone behind her so the occasional defensive miscue would not be so punishing.
Kesler and Kroemhoek (especially Kromehoek have started to adopt to the difference in the speed of the game). Next year, at least one recruit will probably be an upgrade over both of them (Kate Denney).