Gator1,
My belief has been that if you want to engage your back muscles, the closer they are aligned to the direction you are pointing your bow in, the greater the ability to pull your shoulder blades/rhomboids together. As a result you are in a stronger position and with greater leverage to fight collapsing the draw. If you draw a line from one shoulder to the other and the line is pointing to great degree away from the line pointing from the front shoulder to your bow hand. You are probably holding the weight of the bow with more stress on the shoulders.