What is Zero Torque? A Putter Torque Analysis. LAB, Axis1... A Call to Engineers

[MattUtah]

8 hours ago, joostin said:

Well torque is definitely a feel thing which is very subjective, but also varies by amount based on the forces you apply.  So from a scientific view why not get rid of it (certain aspects) as a variable? 

Why not get rid of it? Because getting rid of it means center shafts and onset.  The onset makes them look super shut at address to me. 
 

In theory, if you could remove 100% of torque and have a traditional look and setup, well, sign me up for that. But the shut look caused me to push and pull (and miss) more putts than I was gaining because of zero torque. 
 

Zero torque and the face staying square to path is great - but you can still push or pull that path. The Link.1 worked the best, but even after giving it a long trial, I was less consistent than a traditional blade simply because my alignment was off so much. If something looks closed, you will pull and push to compensate. 
 

I’m in the camp of whatever you aim and align best is probably best for you. I’d prioritize that over torque IMO. 

[JohnBrew]

On 11/6/2023 at 7:49 AM, joostin said:

My only explanation as mentioned before is a lack of build precision throwing the CG a little eccentric.  Very easy to happen if a single or double bend shaft is installed a little off.  LAB should be pretty much perfe

I ran into this problem with an Edel with a double bend shaft that the club builder (NOT Edel) could not get right even after multiple attempts. $500 down the drain.

[ElephantTusk]

On 11/5/2023 at 11:00 PM, joostin said:

Ok here we go.  To look at the torques involved let's first look at a couple macro views, then we'll look at around the shaft axis.  I'm only looking at the start of the putting stroke because it gets complicated, and this is already an involved analysis. 

 

Torques due to weight

 

Here's Tiger face on.  Right now I'm only analyzing at the effects of weight in relation to torques, as if the putter is lifted from the ground at address.  Later we will analyze the effects of the starting motion.

There's torque at the hands in this view (center of rotation at the hands face on) because the putter head CG is normally back vs the grip, and also due to any forward shaft lean.  Reduction of torque here would require forward CG and minimal forward shaft lean.  Torque = Weight of head * moment arm d.

 

Here's Tiger down the line.

There's torque at the hands in this view (center of rotation at the hands DTL) because the putter head CG, and shaft CG, are outward of the hands.  Tiger has upward force countering the weight, and also torque equal to the sum of the weights times their moment arm distances.  It's impossible to get rid of this torque unless you have the hands directly above the club's total CG.  Broomstick putters with the most upright lies would reduce this torque the most, or maybe side saddle.

 

Let's focus on the putter head.  Because of the lie angle, the weight of the head can be broken into an axial force along the shaft and what I'll call an eccentric force perpendicular to the shaft (bending force).  It's just trigonometry to figure this out:

 

That leads us to another view - looking down the shaft axis (get to use my CAD model 🙂), into the hosel.  In this view we can take that force applied to the clubhead CG.  Because the CG's position is eccentric to the shaft axis, there's another torque that the hands have to counteract when lifting the putter:

 

Again, T=F*d.  The farther away the CG from the shaft axis, the greater the torque. 

 

- Putters with toe hang have this torque (mallets would normally have more than blades)

- Face balanced putters also have this torque 

- "Zero torque" and toe-up putters will not have this torque because there's no moment arm.  Zero torque in this view can be CG above or below the shaft axis (see my first post) or better yet directly on the shaft axis - like LAB and Axis1.

 

Torques due to applied forces

 

Ok that's just weight.  How about in the takeaway of the stroke?  Let's look at the macro view again, face on, just focusing on the putter head, not shaft.  To get the head moving from a static start he has to apply torque, T, to get the head of mass m to accelerate, α.  From there the dynamic rotation will be applied by a torque, τ, which is τ = I*α (total club MOI * angular acceleration).  The hands will move in an arc not just rotation, but these are the torques involved at takeaway. 

 

How about the putter head?  Here's the CAD model again from the view we had before to look at torques around the grip at takeaway.  Same thing... there's a torque, T, to start the linear motion of the CG, and then a torque, τ, to rotate the putter head.

 

Torque T would vary depending how fast or abrupt your takeaway is.

 

- Putters with any kind of toe hang, like above, will have this starting torque.

- Face balanced putters will not have this torque because there will be no moment arm between the shaft axis and the CG.

- Toe up putters will have this torque if the CG is above or below the shaft axis

- "Zero torque" putters like LAB and Axis1 will not have this torque either because of no moment arm.

 

The τ torque would be relatively small, as it's rotation around the shaft axis which is dependent in the MOI around that axis and the angular acceleration, and I don't know if anyone rotates the putter all that fast.  Even "zero torque" putters will still have this torque.

 

So in summary the "zero torque" putters are only zero torque in a couple aspects, but there are other torques that will always be involved in the putting stroke.  The zero torque aspects will definitely be a feel thing and up to each person to feel if it makes a difference for them or not.

 

All right, tired.  I did my best to explain things for now.  It's simple but its not!  Anyone with fresh physics, statics, and dynamics in their head, feel free to chime in.  @ThinkingPlus I don't know about the balance on lie angle axis vs gravity axis, but would dig in more if there's truly something there.  I know its coming from the respected LAB, but just not sure as the golf world tends to say scientific sounding things without really being able to show exactly what's behind them!

Awesome analysis, thanks for including the drawings.

 

The face balanced putters would still (very likely) have some torque on the start of the down stroke though, right? The idea here is that if your stroke has any arc or face rotation at all, the fulcrum point (where the shaft applies it's force) and the CG are now misaligned causing torque.

[joostin]

20 hours ago, Soloman1 said:

If you’re interested in dynamic torque during the stroke, that’s more “it depends” on the person and their stroke, visual clues during it, intent, grip, hand, arm and shoulder movements, proximity to the ball, daily horoscope… 😉

For sure, especially those Capricorns.. 🙂

 

20 hours ago, Soloman1 said:

More shaft offset can increase head MOI by as much as 4X, if you’re interested in strike torque and geometry.

That's something I can test in CAD.  Now MOI as reported (like 5,000 g-cm²) is from a vertical axis through the CG, so unless there's a lot of hosel mass, that CG wouldn't change much with different offsets.  If you took MOI from the hosel/shaft/grip axis, yes it'll change, but 4X sounds like a lot.

 

To check that, quick math could use parallel axis theory:  I_shaft = I_cg + Md².  If the shaft axis is 1" away from the head CG, at 5K g-cm² weighing 360g, it's roughly 5,000 + (360*2.54²) = 7,323 g-cm² at the shaft axis.  If you moved the shaft axis 1" farther from the CG, you'd get:  5,000 + (360*5.08²) = 14,290 g-cm²... about a 2X change after moving the shaft axis a full 1".

[joostin]

20 hours ago, MattUtah said:

Why not get rid of it? Because getting rid of it means center shafts and onset.  The onset makes them look super shut at address to me. 
 

In theory, if you could remove 100% of torque and have a traditional look and setup, well, sign me up for that. But the shut look caused me to push and pull (and miss) more putts than I was gaining because of zero torque. 
 

Zero torque and the face staying square to path is great - but you can still push or pull that path. The Link.1 worked the best, but even after giving it a long trial, I was less consistent than a traditional blade simply because my alignment was off so much. If something looks closed, you will pull and push to compensate. 
 

I’m in the camp of whatever you aim and align best is probably best for you. I’d prioritize that over torque IMO. 

I understand, and agree that if there's a confidence or alignment issue overriding anything else you can't get over, then that's more important.  That's subjective.  For those that are comfortable with the look and don't have alignment issues, can feel a significant difference, or maybe even a deep belief or placebo effect of the "tech", they're gonna promote a different view.  Whatever works best you're free to choose!

[joostin]

2 hours ago, ElephantTusk said:

The face balanced putters would still (very likely) have some torque on the start of the down stroke though, right? The idea here is that if your stroke has any arc or face rotation at all, the fulcrum point (where the shaft applies it's force) and the CG are now misaligned causing torque.

Yes spot on.  Depending how much rotation of the head there is at the top of transition, how much CG misalignment vs shaft axis, which way you're applying force, and how much force.  A quick transition will induce more torque at the start of the downswing.  If the transition is slower and lets gravity start the acceleration back down, it'll be less induced torque.

[Stuart_G]

On 11/12/2023 at 2:36 AM, joostin said:

Well torque is definitely a feel thing which is very subjective, but also varies by amount based on the forces you apply.  So from a scientific view why not get rid of it (certain aspects) as a variable?

 

Just speculation and random thoughts.

 

The main reason would be because - if you have thousands of hours with a non-zero torque putter, you've already learned to compensate for any additional application of a compensating torque - and are doing it automatically without thinking.  Changing to a different putter (of any different torque value) requires a change to the mechanics you've learned.   Some might not have a problem adjusting but others might.   And if they didn't have any problem adjusting from a non-zero to a zero, it usually means they also wouldn't have any problems adjusting to the non zero torque putters in the first place.

 

Most of us have been swinging all types of various things with our hands since we were toddlers very few of which were zero torque in the sense you're referring to.   So our ability to adapt is ingrained to some degree in most of us.

 

Also, the swing itself is not zero torque for most.  So the putter swing does require the application of some torque at the handle - even with a zero torque head.   The details of the putter just adjusts the amount required to get the desired action, it doesn't commonly reduce it to zero.

 

 

[joostin]

12 hours ago, Stuart_G said:

 

Just speculation and random thoughts.

 

The main reason would be because - if you have thousands of hours with a non-zero torque putter, you've already learned to compensate for any additional application of a compensating torque - and are doing it automatically without thinking.  Changing to a different putter (of any different torque value) requires a change to the mechanics you've learned.   Some might not have a problem adjusting but others might.   And if they didn't have any problem adjusting from a non-zero to a zero, it usually means they also wouldn't have any problems adjusting to the non zero torque putters in the first place.

 

Most of us have been swinging all types of various things with our hands since we were toddlers very few of which were zero torque in the sense you're referring to.   So our ability to adapt is ingrained to some degree in most of us.

 

Also, the swing itself is not zero torque for most.  So the putter swing does require the application of some torque at the handle - even with a zero torque head.   The details of the putter just adjusts the amount required to get the desired action, it doesn't commonly reduce it to zero.

I do share the same sentiments.  My "why not get rid of it" was more taking the view from the zero torque companies' perspective.  We do after all have the same torques around the shaft axis - that the zero torque putter people admonish and remove - that exist in every other club.  No one bats an eye for those same torques in a precise wedge shot.  It's definitely subjective, so a zero torque putter can be effective or not depending on the person's sensitivities and issues.  And as shown in the diagrams there are swing and rotational torques that will always exist.

[Stuart_G]

4 hours ago, joostin said:

My "why not get rid of it" was more taking the view from the zero torque companies' perspective.

 

Sounds to me more like a marketing department's perspective.  😁

[joostin]

2 hours ago, Stuart_G said:

 

Sounds to me more like a marketing department's perspective.  😁

For sure.  But hey everyone's entitled to their opinion on how it works or doesn't work for them and, and believing who they want to believe.  As long as marketing keeps pumping the science-y narrative and has both backing (success stories, tour usage, Revealer tests) and mystique (people seem to love the term "balanced", and how someone needs to painstakingly perform it), they should sell and carve out a nice piece of the market.  It also seems to help to generate interest by combining different looking designs with a tech story (real and embellished), and actually gaining a real following.  Machine keeps pumping..

[ElephantTusk]

On 11/9/2023 at 8:11 AM, joostin said:

Just wanted to post a “call for engineering analysis" on golf technical things.
Occasionally I feel the need to decrypt golf understandings or terminology with some math and physics.  Whether supporting or not supporting something, try to put some backing to it, and present it here.  “Show your work" and encourage other technical-oriented people to fact check me and fact check the terminology. “What really is zero torque?" for example in this thread.

The reason Dave Tutelman is such a great resource is because he shows the math and physics to a level that no other does.  With all the engineers out there like myself, it’s pretty disappointing that other than him, maybe research papers, and some biomechanics people like Dr. Kwon, there’s almost no online golf presence putting engineering analysis into golf's question marks, claims, and terminology, especially equipment-wise.  Seems not many really care.  Testing things out, like LAB's Revealer is great, but one-off sampling by a biased source isn’t exactly a controlled experiment (though I do believe their results based on the possibility of build inconsistencies with the other companies).  However, concepts can be broken down pretty straightforwardly with engineering analysis - Free Body Diagrams, basic physics equations, use of CAD - things I attempt sometimes on golfwrx.

 

The golf world puts out science-y terminology, and if from a trusted source it’s normally accepted even if not many really show any math or physics to technically back things up.  It's mostly experimental.  So for the engineering and technical people out there:  Come show the math; fact check mine; fact check Tutelman’s; fact check others; come up with your own; come out of the woodwork!

 

It’ll do the golf world some good, especially in a forum setting, for more engineering type analysis.  Rather than just science-y lingo and evidence, or simply accepting something because a trusted source said so (even from the revered Wishon, Maltby, Solheim, …), let the unbiased math and physics speak.  Then we can de-mystify things and determine what’s really behind them like I attempted above with “zero torque”.

 

If curious, here is the original US Patent filed in 2013: https://patentimages.storage.googleapis.com/58/25/ed/a5e3d51d76f15f/US9233280.pdf.

 

Should hopefully help clarify CG placement wrt the shaft and exactly how lie angle changes the relevant torques.

[ElephantTusk]

The interesting thing to note is that the shaft explicitly does not just intersect the center of gravity as some have claimed: the required offset is determined by the lie angle and the vertical difference between where the shaft is physically mounted and the center of gravity (emphasized in figure 4).

 

This patent just specifies the findings and specifications, but not the proofs for why this produces zero torque during a stroke (as more or less defined by the design and use of "the revealer"). So that would definitely be interesting to derive.

 

Takeaways seem to be that

 

1) changing the weights yourself would very likely change the CoG, the required placement of the shaft position, and therefore the lie angle balance.

2) within some reasonable tolerance (so as to not "significantly" alter the effective CoG), changing grip and length should be fine. Note, however, that because the regular and armlock putters are flatter, I would expect them to be slightly more sensitive to changes in length than the broomstick putters.

Edited November 17, 2023 by ElephantTusk

[joostin]

7 hours ago, ElephantTusk said:

 

If curious, here is the original US Patent filed in 2013: https://patentimages.storage.googleapis.com/58/25/ed/a5e3d51d76f15f/US9233280.pdf.

 

Should hopefully help clarify CG placement wrt the shaft and exactly how lie angle changes the relevant torques.

Thanks! Will look into it

[tcbringhurst]

1 hour ago, HighHooks said:

Axis1 is the only company to accomplish this

And LAB hasn’t?

[tcbringhurst]

1 hour ago, HighHooks said:

 

 

From the first post by Joostin in this thread. 

 

"Axis1 goes a step further in getting CG forward and on with the face, which IMO is the most technically advanced CG location.  Center impact is directly on the CG, and there's zero gear effect on off-center hits when CG is directly on the face, only when it's behind or away from the face.  So there would be no induced gear spin on an Axis1 putter, however little is actually there."

 

That's what's I believe Luis is referring too.

Can these putters be balanced on the face? Meaning like one of those balancing toys, I would be able to put my finger on the center of the face and hold the putter up with just my finger on the face?

[tcbringhurst]

35 minutes ago, HighHooks said:

Like this?

Anyone could put their putter on a point and be holding the butt of the club off-camera

[Stuart_G]

On 11/16/2023 at 12:43 PM, ElephantTusk said:

This patent just specifies the findings and specifications, but not the proofs for why this produces zero torque during a stroke (as more or less defined by the design and use of "the revealer").\

 

Patents don't require any proof or validation.   That's why scientific journals are much better sources for scientific advancement and patents are really a crap shoot.

 

[ElephantTusk]

2 hours ago, Stuart_G said:

 

Patents don't require any proof or validation.   That's why scientific journals are much better sources for scientific advancement and patents are really a crap shoot.

 

 

Yeah understood.

 

But to the extent to which 1) LAB is actually implementing that patent and 2) the videos with "the revealer" are not fake, then that patent includes specifications for how to "lie angle balance" a putter, and the derivation of the coordinates specified in the patent should lead to a deeper understanding of what torques are being zeroed out and how sensitive that is to changes in grip weight or shaft length.

Edited November 17, 2023 by ElephantTusk

[tcbringhurst]

38 minutes ago, HighHooks said:

 

You do realize Flanigan Built Putters, not axis 1, is who did that study? See Quintic Robotic Testing earlier in the thread about the CG location too.  

 

Yes I watched it

 

if the center of gravity was in the clubhead at the face, he wouldn’t be able to balance the club like this in his hands. It would fall off his hands towards the clubhead. But since it doesn’t fall off in the video, the center of gravity is somewhere between his fingers. 
 

Maybe I’m misunderstanding CG in this context

 

 

Edited November 18, 2023 by tcbringhurst

[tcbringhurst]

54 minutes ago, HighHooks said:

 

You do realize Flanigan Built Putters, not axis 1, is who did that study? See Quintic Robotic Testing earlier in the thread about the CG location too.  

 

And looking at Flanagan’s posts, they show many other putters with a CG in the same spot as Axis 1

[Stuart_G]

12 hours ago, ElephantTusk said:

 

Yeah understood.

 

But to the extent to which 1) LAB is actually implementing that patent and 2) the videos with "the revealer" are not fake, then that patent includes specifications for how to "lie angle balance" a putter, and the derivation of the coordinates specified in the patent should lead to a deeper understanding of what torques are being zeroed out and how sensitive that is to changes in grip weight or shaft length.

 

Sorry, but I'll have to disagree.  Sporadic hand picked anecdotal evidence has little statistical strength and doesn't really provide much support for the concept.   It's way too easy to document the success and ignore the failures.   Even in the presence of strong statistical data (if it ever does exist) wouldn't necessarily expand the understanding of what's actually happening and why - any testing with human's adds way too much complexity to the possibilities that may be influencing the results.

 

[joostin]

12 hours ago, tcbringhurst said:

Yes I watched it

 

if the center of gravity was in the clubhead at the face, he wouldn’t be able to balance the club like this in his hands. It would fall off his hands towards the clubhead. But since it doesn’t fall off in the video, the center of gravity is somewhere between his fingers. 
 

Maybe I’m misunderstanding CG in this context

 

 

To clarify, the CG that Axis1 says they bring to the clubface is the CG of the head alone, not the CG or balance point of the whole club.  The real way to test is to remove the shaft, and balance the head two ways - on a point on the face, and also on a point on the sole.  Balancing on the sole might be hard to do because the balance point should be up near the face.

 

Alternately, if you take the whole assembled club, you can do a toe hang test on a table.  An Axis1 should (hopefully) be able to "hang" with the toe pointing in any direction (same with a L.A.B.), AND the main shaft axis should point straight to the center of the face.  They would be unique to this because of all the head mass they put in front of the face.

 

The balance point on face test in the Flanigan pic above only shows the head CG aligned with the sight line, but nothing about how forward the CG is, and the shaft/grip is definitely being held.  You should be able to do the same with most putters if they align their sight line with their head CG (away from the face).

[ElephantTusk]

4 hours ago, Stuart_G said:

 

Sorry, but I'll have to disagree.  Sporadic hand picked anecdotal evidence has little statistical strength and doesn't really provide much support for the concept.   It's way too easy to document the success and ignore the failures.   Even in the presence of strong statistical data (if it ever does exist) wouldn't necessarily expand the understanding of what's actually happening and why - any testing with human's adds way too much complexity to the possibilities that may be influencing the results.

 

 

Lol, bruh. What statistical data are you talking about?

 

If you believe those LAB videos with "the revealer" are fake, then just say that. If they are not fake videos, then those putters do behave differently than conventional face balanced or toe hang putters. No stats, just different physical properties as (presumably) detailed in the patent. Simple as that.

[Stuart_G]

2 hours ago, ElephantTusk said:

 

Lol, bruh. What statistical data are you talking about?

 

The non-existent data that would be required to provide any kind of support for the speculation of the designers.

 

2 hours ago, ElephantTusk said:

If you believe those LAB videos with "the revealer" are fake, then just say that.

 

I never said anything about the videos being fake.    The revealer is just a tool that shows that the design goals were met.   At best it's a gimmick.   It doesn't validate the concept that non-"zero-torque" putters actually cause any problems in the putting stroke or that "zero torque" putters necessarily provide any kind of improvement to actual putting results for all individuals (the speculative parts in the patent).

 

Edited November 18, 2023 by Stuart_G

[Soloman1]

I’ll bet I could create a marketing campaign for a high-torque putter.

 

Make 17.4% more putts with the HT Max™

 

Agree completely with Stuart’s comment on human variability and adaptability.

 

Yes, less torque in a head is a good goal, particularly for off-center strikes. Other putters may have other goals.

 

The consumer would be better served with robot tests of different putters to measure proximity to the hole at different lengths with the same offset distances from the center horizontally and vertically.

 

It’s results that matter, right?

 

But that isn’t done. Human testing shows the person adapting to the result of the first putt on subsequent putts.

 

I brought this testing up before somewhere here long ago and was soundly chastised for being a complete moron.

 

The dance between marketing and “technology” ends up with marketing leading the dance.

 

Here’s an analogy to consider. In the world of luxury brand jewelry, watches, handbags and clothing, the overwhelming majority of customers are not people who can afford it easily.

 

The overwhelming majority are people who really can’t afford it, but want to appear to others that they can.

 

You could make the ugliest, worst performing putter on the planet. If it was expensive and had the name Scotty Cameron on it, or Tiger Woods used it, it would be a massive hit.

 

The recreational golfer will always do better with a putter that fits them, fits their stroke, visual clues, grip, weight, etc.

 

For a few rounds…

 

 

[ElephantTusk]

4 hours ago, Stuart_G said:

 

The non-existent data that would be required to provide any kind of support for the speculation of the designers.

 

 

I never said anything about the videos being fake.    The revealer is just a tool that shows that the design goals were met.   At best it's a gimmick.   It doesn't validate the concept that non-"zero-torque" putters actually cause any problems in the putting stroke or that "zero torque" putters necessarily provide any kind of improvement to actual putting results for all individuals (the speculative parts in the patent).

 

 

Gotcha. I think we are just talking about two different things then.

 

From my perspective it's a very interesting design just to understand the physical properties alone - it's neat to have the putter face naturally stay square to the path (by design) without needing to apply counter forces (with your hands) to keep it square.

 

I guess you're talking about analyzing data on if golfers actually make more putts with it, which is a very understandable question. It would be tricky to design that experiment, and not something I've mentioned in any of my posts.

[ElephantTusk]

2 hours ago, Soloman1 said:

I’ll bet I could create a marketing campaign for a high-torque putter.

 

Make 17.4% more putts with the HT Max™

 

Agree completely with Stuart’s comment on human variability and adaptability.

 

Yes, less torque in a head is a good goal, particularly for off-center strikes. Other putters may have other goals.

 

The consumer would be better served with robot tests of different putters to measure proximity to the hole at different lengths with the same offset distances from the center horizontally and vertically.

 

It’s results that matter, right?

 

But that isn’t done. Human testing shows the person adapting to the result of the first putt on subsequent putts.

 

I brought this testing up before somewhere here long ago and was soundly chastised for being a complete moron.

 

The dance between marketing and “technology” ends up with marketing leading the dance.

 

Here’s an analogy to consider. In the world of luxury brand jewelry, watches, handbags and clothing, the overwhelming majority of customers are not people who can afford it easily.

 

The overwhelming majority are people who really can’t afford it, but want to appear to others that they can.

 

You could make the ugliest, worst performing putter on the planet. If it was expensive and had the name Scotty Cameron on it, or Tiger Woods used it, it would be a massive hit.

 

The recreational golfer will always do better with a putter that fits them, fits their stroke, visual clues, grip, weight, etc.

 

For a few rounds…

 

 

 

I mean yeah, use whatever putter you make more putts with - no one has suggested otherwise. Did you read the title of the tread, though?

 

It's a "call to engineers" to talk about the physics of these putters, at least as far as I understand.

[Soloman1]

9 minutes ago, ElephantTusk said:

 

I mean yeah, use whatever putter you make more putts with - no one has suggested otherwise. Did you read the title of the tread, though?

 

It's a "call to engineers" to talk about the physics of these putters, at least as far as I understand.

 

Thanks for being a volunteer moderator and thought leader to keep us in check.

 

Topics resolve into other things after the meat has been said. I’m a Mechanical Engineer who makes putters. How about you, sparky?

[ElephantTusk]

2 minutes ago, Soloman1 said:

 

Thanks for being a volunteer moderator and thought leader to keep us in check.

 

Topics resolve into other things after the meat has been said. I’m a Mechanical Engineer who makes putters. How about you, sparky?

Ha, has the meat already been said? I didn't catch the resolution I guess.

 

Legit interesting background, though. Don't misunderstand me as questioning your intellect, just that I don't see the relevance in the observation that one can market various different things to the general public.

[Stuart_G]

13 hours ago, ElephantTusk said:

I guess you're talking about analyzing data on if golfers actually make more putts with it, which is a very understandable question. It would be tricky to design that experiment, and not something I've mentioned in any of my posts.

 

That's part of it of course, but I also think the approach looks at an over-simplified view of the dynamics and biomechanics of the swing itself.  Possibly making some assumptions that might be best if they were not made.  Hard to say for sure though since little is said or published about that aspect of things.