I feel as if I have reached a breakthrough, and it seems minor, but I feel as if I understand what base is necessary for one to do well in Crossfit. I extends beyond Crossfit, though, to anyone looking for a good level of physical well-being. It is also vital to most athletes.
This 'magic' is the melding of strength and flexibility, and everyone that claims they are mutually exclusive does not understand the mechanics of the body. Flexibility allows the body to move and strength causes those movements. An increase in both will improve your quality of life far outside the doors of the gym, but I'm more concerned with the goings on in the gym.
If you are not flexible then you have no business doing a laundry list of strength exercises that are brutally effective movements to include anything Olympic, Back Squats, Overhead Squats, Thrusters, and if you can't keep those heels on the ground during the hip break you should not be doing Push Presses. When you are working with weight of any significance your weight needs to be on your heels because that is where you are most stable. Stable is good, stable prevents you from falling over and throwing a loaded barbell and some poor guy's head. Of course, being able to display this ability requires flexibility in the hams, calves, and Achilles tendon. If this is a weakness, then check the ego at the door and use a light load and do various forms of stretching based around the necessary mobility.