pressure comes from precision: We tend to think of pressure as the result of the power of our weight and muscles being applied to an opponent. But in truth, precision with positioning of your body on to the appropriate areas of your opponent's body is far more important. You can be big and heavy but if you don't know how place and hold your weight, a skilled opponent won't feel much pressure and easily escape. Conversely, you can be of modest size and strength but if you know exactly how to use your weight and position it, you can feel like a truck parked on an opponents chest. Just as the effect of a boxers punch is mostly determined by its accuracy and timing rather than size and strength, so too with grappling where the exactness of placement, how well you conform to the opponents body and how you apply the weight you have determines pressure rather than your gross weight.
