Interesting foot action in left foot alright. I think if he started with left foot more flared out (ala Ben Hogan), he would not have to change the relative position of it mid-swing. Seems like it is an involuntary adjustment of his left ankle, knee, and hip joints to realign and thus allow for the hip rotation and lateral slide necessary for him to shift his plane and swing through the ball the way he does. I wonder if Tiger might take some of the stress off of his left knee and benefit from a similar adjustment at his address position. Anyway, just a couple of thoughts that occurred to me. Thanks for posting such great pictures!