Unfortunately the term "head down" is the biggest culprit here.....
Relative to the shoulders, the head can only rotate about 70 degrees to either the right or the left......
This means, on your downswing, with your head facing down at the ball, once the right shoulder has closed the angle to that 70 degree position, there is no choice but for the right shoulder to "collect" the head and rotate it to the left....
However, at that point, the right arm is nearly pointing straight down the target line (depending on head position at impact), but it is well after impact...
Therefore any strain on ther neck muscles from "holding the head down" are caused after impact...
Take a look at Ernie's swing (you can see his stills on the latest Callaway ad)...you will see that his head is collected well into the follow through (watch hiim in slo.mo too...
)
Perhaps it would be better if teachers stated to keep the "eyes gently down" or "head gently steady", rather than head down, which implies a force...
From my own perspective, I have tried releasing the head earlier, but find it leads to big pushes and inconsistent ball striking, as there is a tendency to come out of it too soon...
I think it may be an OK move for people who can hit a
lot of balls in practice (like pros), but maybe not for the average player...