ChrisHein

There is a gap behind your head that you are leaving wide open for them to roll out of. If you close this gap off, they can't roll out of it anymore. However if they are consistently rolling out, and you can't make the technique good enough to stop them, you can simply plan a good follow up technique. Depending on what they are doing yonkyo or sumi otoshi might work very well in this situation as a follow up technique.