Only one position truly merges position and – the back: If you look at the of Jiu jitsu you will that as desirable as they are – you still have quite a bit of work to do to go beyond the pin into the submission. Getting pin or mounted or north south or knee on belly is good, but getting the arm or from there requires a significant set of skills. The rear mount on the other hand leaves you VERY close to submission. Unless your opponent has good a simple wrapping of your arm around the neck is enough to end it. You can see how closely the position (rear mount) is to the submission (rear strangle) by the fact that the escape from one entails the escape from the other. This is not true for say, a mounted arm bar or from side or knee on belly. Usually escaping the pin is one thing, the submission from that pin is another. As such rear mount/rear strangle is the single best synthesis of position and submission in the sport. Mastering the art of getting there, staying there and finishing from there is the best way to close the gap between position and submission in your game