Points
In my opinion, I feel that a couple of the +0 body parts should be higher due to real life significance, but then again keeping it like you have it centralises this mod around being able to block well, and rewarding those who can aim for and hit the relevant body parts. For example the shins, if hit with enough force, you would FEEL THE PAIN, along with a precise jab above the knee cap, but of course with enough force anything can emit pain. Although again, I see that you've done what you've done to limit the types of openers which deal stupid amounts of damage initially.
Areas such as the chest and ribs protect the lungs, and thus I would think that they would be more vital parts of the body, along with the stomach. However keeping it as you have it ensures that it's not too complicated, and 'any hit' will return a stable amount of points.
One question, will there be dislocations possible? And with them, how many points?
Perhaps raise the points which you currently have to 200%, which would allow you to increase the points received when hitting certain joints - by half.
ie head 10, chest 2, shin and or knee 1, pecs 2, abs 2, etc 0
Points