It's tempting to say it's all about positioning. Ok yes, he could be taking a safer lines through the corners, given how many times he's been taken out like that. However just looking at his positioning in both Giro and Vuelta crashes, which were similar in nature, there was nothing out of ordinary in his positioning prior to the crash:
View: https://www.youtube.com/watch?v=qqYsfZFOp-0&t=2m53s
Pause this video at 2m 53s. Nothing he did that wasn't done by literally dozens of other riders in that very same corner yet he's the one who gets hit by another rider. Again. I'm all for maximising your chances of staying on your bike but it really does look like just a lot of bad luck to me.
Same thing goes for G. Nothing wrong in his positioning and nothing he could do to not get hit.
Ok maybe there are riders who keep their balance better after getting hit. And maybe their teams could surround their leader so that there would simply be no rider in their vicinity without an increased interest to stay on their bike for their leader's sake..