Commentary on Wayne's analysis of Ben Hogan's clubshaft shallowing move - Part 1

Wayne,

You made the following comment in a previous e-mail message-: "You will note that most great ball strikers shallow the shaft early in transition and for a short period of time (during the period between 3.8 and 4.5) and then complete the forward swing to impact by gradually steepening the shaft."

You then attempted to demonstrate that phenomenon in your video analysis of Ben Hogan's golf swing.

In your description of the clubshaft shallowing move, you seem to be implying that the clubshaft becomes off-plane during the early downswing (so that an imaginary line extending out from the butt end of the club points outside the ball-target line), and that it then becomes on-plane again in the mid-downswing as the golfer subsequently steepens the clubshaft. Although I can agree with you that your described phenomenon happens in a small subset of PGA tour golfers, I think that the majority of PGA tour golfers can shallow the clubshaft during the early downswing while remaining on-plane. I would imagine that you will immediately disagree with my last claim because your definition of a clubshaft shallowing action is a situation where an imaginary line extending out from the butt end of the club points outside the ball-target line, which means that it is off-plane (and not on-plane). Before I analyse your description of a clubshaft shallowing action, note that my personal definition of a clubshaft shallowing action relates the motion of the clubshaft relative to the hand arc path, and I believe that the clubshaft shallowing action can be an on-plane phenomenon, or an off-plane phenomenon (if the degree of clubshaft shallowing happening per unit time is greater than the amount needed to still maintain an on-plane clubshaft). See this short review paper - http://perfectgolfswingreview.net/VP6.html - where I describe how, and why, many pro golfers shallow their clubshaft during their early-mid downswing. I use a number of pro golfers as examples, and they all shallow the clubshaft between P4 and P5 (relative to their hand arc path), but they all keep the clubshaft on-plane during their clubshaft-shallowing action. You do not use the hand arc path as the reference point for definining a clubshaft-shallowing action, and you base it on lines drawn down the length of the clubshaft, while noting two points - i) that the clubshaft angle changes (shallows) between P4 and P4.8  and ii) a line drawn out from the butt end of the clubshaft at P4.8 will seemingly strike the ground at a point outside the ball-target line.

So, let's consider your video analysis of Ben Hogan's swing.

Here are capture images from your video.

Image 1 represents the P4 position, and you have drawn a red line from the butt end of the club to the ball. That line measures 60 degrees. That line goes just below Hogan's right shoulder, which means that his hands are on a plane that is slightly shallower than the TSP. By drawing that red line in that way, you seem to be implying that the butt end of his clubshaft is pointing at the ball, but that is not possible (even if the clubshaft is on-plane) because it must be pointing far more backwards towards a point on the ball-target line (presuming that it is on-plane) that is many yards further away from the target.

Image 2 is at P4.8. You have drawn a line down the length of his clubshaft and extended that line outwards. That line measures 40 degrees. You have then seemingly concluded that Hogan has shallowed his clubshaft by 20 degrees between P4 and P4.8. Because that projected line points outside the ball-target line, you have also seemingly concluded that the clubshaft shallowing action (of 20 degrees) causes the clubshaft to become off-plane. I believe that both conclusions are scientifically invalid. I think that your fundamental mistake is that you are willing to draw those lines on a 2-D image when the clubshaft is not parallel to the camera lens, and that you are wrongly concluding that those red lines accurately reflect where the butt end of the club is really pointing. I believe that it is not possible!

I believe that those drawn red lines can only be accurately reflective of reality when the clubshaft is parallel to the camera lens - as seen in image 3. Between P4.8 to P5.2, the clubshaft is either parallel to the camera lens, or close to being parallel, and therefore drawing a line outwards from the butt end of the club in the direction of the ground can accurately reflect reality. Note that the white line (drawn down the length of the clubshaft) in image 3 points at the ball-target line, which means that the clubshaft is on-plane.

Also, to prove my point that a 20 degree change in clubshaft angle between P4 and P4.8 doesn't automatically imply that the clubshaft is shallowing - consider the following presentation.

Video of a golf robot - https://www.youtube.com/watch?v=AN4fSnf8TBY

Here are capture images of the golf robot performing a driver swing.

I have labelled each image with two pieces of information - i) the P position, and ii) the angle of the clubshaft.

I presume that you agree with two points - i) that the golf robot has a single plane golf swing (zero-plane shift golf swing) with no clubshaft shallowing action and ii) the clubshaft is always on-plane (which means that the end of the club that is nearest the ground will always be pointing at the ball-target line - when the clubshaft is not momentarily parallel to the ball-target line).

Now, can we draw lines outwards from the end of the club (that is nearest the ground) and look to see whether it points at the ball-target line - thereby signifying an on-plane clubshaft? I believe that it only possible when the clubshaft is roughly parallel to the camera lens, which usually happens at ~P5 and at P7. Note that the measured clubshaft angle is identical (52 degrees) in both those P5 and P7 images. Note that the clubshaft angle of 51 degrees at P5.5 is close to the 52 degree angle, which is not surprising if the clubshaft is not shifting planes and if the club lag angle has not changed much between P5 and P5.5.

Now, consider an interesting fact - that the clubshaft angle changes by ~13 degrees (in a shallowing direction) between P4 (where it measures 70 degrees) and P4.7 (where it measures 57 degrees). We know that the clubshaft is not really shallowing between P4 and P4.7 and that it is always on-plane (on a fixed plane), so what accounts for the 13 degree of "apparent" clubshaft shallowing?

I think that the changing angles only reflect the fact that the clubshaft angle (as viewed from a DTL perspective) is obviously changing between P4 and P4.7 because the central arm (equivalent to the left arm) is moving downplane, which means that the clubshaft is also moving downplane in 3-D space. None of those angles reflect reality (indicating where the clubshaft is really pointing in that 2-D image) because the clubshaft is not parallel to the camera lens. Note that the angles are moving in the general direction of 52 degrees (where the on-plane clubshaft is parallel to the camera lens), which is in a shallowing angle direction - but those progressively shallowing angles does not mean that the clubshaft is actually shallowing out (because clubshaft shallowing is physically impossible in the golf robot's single-plane golf swing action).

Why are the 70 degrees and 57 degree angles different to Hogan's swing? That is not surprising because Hogan's left arm is much shallower than the Golf Robot's central arm (left arm) at P4 and at P4.7.

Consider this photoshopped image.

I used Photoshop to superimpose a copy of the P4.7 image on top of the P4 image, and I then used the free transform tool to tilt the central arm groundwards to a slightly shallower plane. That will obviously shallow the clubshaft angle (which now measures 40 degrees and not 57 degrees), and a line extended out from the butt end of the club will also move more outwards (to beyond the ball-target line). That line cannot actually reflect the "true life" reality of where the clubshaft is really pointing because the clubshaft is angled away from the plane of the front of the camera lens. The only point that I am trying to make is that one could design a golf robot where the plane of the central arm's zero-plane shift motion is on a shallower plane, which will cause the 70 degree angle at P4 to measure closer to 60 degrees, and the 57 degree angle at P4.7 to measure closer to 40 degrees. Would that cause the shallowing-difference of 13 degrees to become greater, and closer to 20 degrees? It may, and it would not surpise me if that happended. In other words, it is possible that the 20 degree angular difference between Hogan's P4 and P4.8 clubshaft angles may have nothing to do with any "real life" clubshaft shallowing action that can potentially move the clubshaft off-plane. The burden on you is to prove that some fraction of that 20 degree angular change between P4 and P4.8 in Hogan's swing is truly due to a "real life" clubshaft shallowing phenomenon that really moves the clubshaft off-plane.

You also have to make more sense regarding those lines drawn out from the end of the club that is nearest the ground.

Consider this composite capture image from the Golf Robot video.

Image 1 is at P4. Note that the blue line drawn out from the clubshaft seems to hit the ground well inside the ball-target line. That's obviously an "artifact" due to the fact that the clubshaft is not angled parallel to the camera lens, and we know that the imaginary line must really be pointing at the ball-target line because the clubshaft is always on-plane.

Image 2 is at P4.7. Now, the blue line is moving in the direction of the ball-target line, which is not surprising because the clubshaft is 13 degrees shallower at P4.7 compared to P4. That blue line still cannot reflect "true life" reality because the clubshaft is not parallel to the front of the camera lens, and we know that the imaginary line must really be pointing at the ball-target line because the clubshaft is always on-plane.

Using your technique of drawing lines outwards from the butt end of the club (when the clubshaft is not parallel to the camera lens) is a very unscientific technique that is very problematic in terms of representing "true life" reality. I think that you need to solve this problem, and I am very open to analysing any of your further suggestions and any other feedback (if you disagree with any of the points in my presentation).

Finally, have you ever traced Ben Hogan's hand arc path to see how his clubshaft shallows-out relative to his hand arc path.

Here is an example.

The red splined path represents his hand arc path. His left arm is at the P4.8 position. Note the small degree of clubshaft shallowing that exists relative to the hand arc path.

Where do you think that an imaginary line extending out from the butt end of his club is pointing? I personally suspect that the imaginary line is pointing in the direction of the ball-target line and that his clubshaft is on-plane at P4.8 in that particular swing action.

Jeff.