So if I understand it right, the flexed right knee straightens a certain amount during the backswing, but doesn't straighten completely. Now, are the knees at address flexed loose, or with a certain amount of tension, that you feel throughout the backswing?
My problem is at the moment that I completely straighten my right leg (and the whole body) throughout the backswing. On some days I hit really good shots, some days I start shanking the ball. A South African Pro told me last year my shanks were caused by straightening my right leg (too much), I remembered his advice today and flexed my knees with more tension in the backswing with the results of hitting decent shots again. Can somebody confirm or explain why a straightened right leg can cause shanks?