Only one truly merges position and submission – 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 to do to beyond the pin into the submission. Getting side pin or mounted or north south or knee on belly is good, but getting the arm or neck 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 defensive skills a simple wrapping of your arm around the neck is enough to end it. You can 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 Kimura 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 is the single best synthesis of 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