So, in thinking about leg locks lately, from the ground up as they say, I have been mindful of the importance of where one places one's feet. For instance, if you are in bottom half guard and you figure four your feet, then you inadvertantly give up what will become your secondary leg if your opponent either backsteps or frontsteps into reverse half mount. Check out Keenan Cornelius' ingenious "knee bar trap" series here. You'll see what I mean. Once you've trapped your own foot, I can take advantage of that by keeping it there and then you lose your secondary leg--making it nearly impossible to defend the knee bar once I drop to the side to finish.
Today, while watching people roll, something dawned on me that I had never thought of before--namely, that it matters which way you cross your feet when you have someone in your closed guard. I never thought it made any difference, so I have always been in the habit of crossing them the same way. It seems I was overlooking something important. Imagine I have my opponent in closed guard and I have a cross collar grip with my left hand. Given my hand placement, my opponent is going to try to pass to my right. This means he will also be trying to pry my feet apart by pushing down on my right leg. If I have my left leg crossed over my right leg, then this makes it easier for my opponent to pry my feet apart by pushing down on my right knee or inner thigh (since there is nothing in the way). However, if instead I cross my left leg under my right leg, it now serves as an extra barrier that reinforces my crossed feet. After all, when my opponent pushes down on my right leg, my left leg is in the way (much as we do when defend the armbar with our other arm). Having given it some more thought, I thought a nice way of remembering this is as follows: When I cross grip with my left hand, my right foot goes on top. Conversely, when I cross grip with my right hand, my left foot goes on top. Perhaps an even more general principle would be: Whenever your opponent is trying to break your crossed feet by pushing down on one of your legs, make sure that leg is on top of your other leg.
Thoughts? This escaped my notice for 13 years--which is surprising. Has anyone ever been taught that it matters which way your feet are crossed from closed guard? Try it out and see. I tinkered with it for a few minutes earlier and it seems to make a difference. But because I can't train, I couldn't test it under more realistic circumstances.
p.s. Sorry I didn't/couldn't just make a video--which would make it easier to demonstrate and explain!