Rather than have to write a whole new post, I'll just efficiently recycle one of my comments from scarbs blog....
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If you look-back at the early races, Lewis doesn’t really do the the shuffle-down.
Bahrain there is perhaps a very early prototype of the move on the front straight, but not yet the full-monty, in Oz he does occasionally very slightly lower his left hand on some straights, but it is minimal, he still remains firmly hooked through the thumb hole.
But by China down the back-straight he is pretty much doing the complete lazy-left (as this move will now certainly be styled). Not quite, but almost the finished article.
If I was forced to have a bet, and without a decent photo of the cockpit we are all still guessing, I’d suggest that it is just a comfort/relaxed light-touch thing that he is experimenting with.
There is still a distinct lack of any lateral movement.
Obviously the right hand can’t participate due to upshifts on the straight.
Could be an elbow-duct?
Perhaps the left leg thing is not quite as optimal as we all think, but McLaren wanted to keep the action hidden; however once they saw Ferrari not penalised by stewards for driving no-hands, they moved the duct into the cockpit … but that doesn’t match with the gradual and progressive evolution of the new grip from season start, and only one driver.
And if there were a new option available, I’d have thought it would be the taller, more cramped Button that would be first to switch from leg to arm, not Hamilton. He is still sitting high and his legs must be jammed in there.
Anyone got a really clean photo into the left-hand side of the cockpit? Nah, doubt it.
Either way, for comparison, for what it’s worth, here is 10minutes of Jenson not much moving his left hand at all as he circulates the Turkish track:
http://www.youtube.com/watch?v=bbeNokhlTbI
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So after all that, who knows ... I doubt it, but I wouldn't bet my life on it, because it does look a bit new and strange, and definitely the action gets a bit busy going into braking zones and tight corners.
Here is another video, where Hamilton is talking through the new wheel, and mentions that the open-bottom horns were his idea, so maybe it is just a personal preference, comfort thing.
http://www.youtube.com/watch?v=tcMvt0rO20g