Short Realization About Passing

I was training the other day and I came to a realization on passing the guard. Maybe I'm an amateur because I just realized this, but in case you haven't yet, here you go.

The guard is a position where you use each of your limbs, gravity, hip movement, etc... to create angles and get into different position where you can sweep or submit your opponent. In order to pass the guard you need to either take advantage of a mistake a guardplayer makes or create an opportunity to pass. The realization I made is that you need to really isolate the hips, prevent them from moving and turning. Doing this will make your opponent's legs less effective and reduce the chance of being swept or submitted. I know this is something that I do regularly but I never realized exactly what the purpose of me pinning my opponent's hip to the mat was other than simply allowing me to pass.