I dont' get enough mat time to try this....1st I'm sure this isn't rubber guard. This is more of an omoplata while underhooking your own leg to get more weight and control on that shoulder. It looks pretty clever along with looking pretty damn effective. Underhooking the shin seems to have put all the weight on that shoulder. Then when triangling the legs, it looks like the arm in reduced the space and allowed the triangle to have a tighter grip. The only down side to it is that you have a hand trapped as well.