100% agree with this. Left foot being flared allows greater range of motion for the left knee, it can flex forward longer and rotate left (open up).
Video below, note where the pressure is tracing, towards the toes of the left foot. @march11934, your's would be going more towards the left heel because of the way the left knee works.
Good drill to do for the left knee/Key #2 (Weight forward)
OK sot there were some points I am not following. There are a number of theories including Pete Cowen's about striking down on the ball. How is this achieved if the ball is forward of center? From watching Stenson he seems to place the ball farther back in his stance than most relative to each club and hits down into the ground. He uses a full body turn and drives down. HIs release is low and around his body rather then around his neck because of how he makes his arms and torso as one unit. I have been trying to emulate this. If the ball is placed forward you either need to slide forward on the foreswing to get the ball in the downward arc or you end up hitting the ball in the upward portion of the swing? You really see me flipping at the ball? That would be a casting motion correct? So that would mean that the club head has gotten in front of my hands with the ball back in my stance? Im not following how this is being seen.