I never did try more to the rear of the quad, but always tried to go for the deepest belly of the quad muscle instead. Technically, you can put the pin anywhere so long as you don't hit a major nerve like the sciatic or nail tendons, ligaments, or bone....OUCH!!!!!
*** It is easier to ponder the universe and its nuclear furnaces dancing their violent ballets across the heavens to the chaotic requiems played by quantum physics than it is to fathom the inner universe and complexities of the human body, mind, and spirit. *** Spook