Grip pressure and club face control go "hand in hand", as it were.
The left (lead-side) thumb controls the putter face, for a well-trained putter, not grip pressure. Overall grip pressure is simply a mechanical connection of the body and the putter (handle). Changes in grip pressure during the stroke come about for different reasons, but grip pressure changes per se are not the cause of faulty strokes. And what is causing variable grip pressure, by the way, adversely affects BOTH line control and pace / distance control.
The putting stroke involves only two values: line and distance. Tempo, rhythm, impact velocity -- anything in the TIMING of the motion -- all relate solely and exclusively to distance control. Line control does not involve TIMING and any teaching that advocates changing timing for the sake of line control is, in my view, ignorant and unsound. Therefore, LINE control is exclusively path and putter face orientation thru impact.
So for line, with any timing (even incorrect timing with impact velocity too fast and the pace too quick and the distance too far, or the opposite), LINE control is only a square putter face (same orientation in external world at and thru impact as aimed at address) moving any piece of the putter head straight down the aim line (not necessarily the sweetspot).
That means that every good stroke accurate for line and distance has this square face moving straight thru the ball on the aim line, with the usual good tempo and rhythm generating the appropriate impact velocity for the distance, green speed, and elevation difference of the particular putt. Every stroke is "straight wherever aimed with the usual tempo-rhythm". That makes a "gun that always shoots straight wherever aimed, with the right amount of gunpowder in the bullet".
Whether the putt sinks or misses (neglecting rub of the green) depends only on the correct read and aim for that putt, not upon an incorrect read or aim "fixed" by a funny stroke for line and/or pace timing.
Unfortunately, probably 90+% of golfers, pros included, have uncertain reading and aiming skills, and that requires them chronically to be employing "funny" strokes for line or pace to try to make the putt work out.
All that said, we can consider "re-gripping" in mid-stroke.
The different contributing causes of re-gripping are many: a) bad grip designs, b) bad grip form, c) bad grip pressure, d) bad knowledge of the skill for grip, e) absence of knowledge of what is the line-control priority for body control in posture and movement, and f) making "funny strokes" to fix not-so-hot reading and aiming. Of course, plain neurological dysfunction is another cause.
BAD GRIP DESIGNS
Historically, grip companies simply aped what was selling. Early on, the grips were FULL SWING grips held in the fingers, not in the palms as often used for putting. So putters were fitted with the usual thin grips, leather wraps and later plastic / rubber / elastomers. These grips made for holding in the fingers as in the full swing clubs were inappropriate for putting to begin with. So that's bad. In the 1950s and 1960s, people started experimenting with inventive grip forms that the established companies did not welcome. The PISTOL grip form was one of those. After it caught on, coming out of the entrepreneurial realm into the default of the established companies, the established grip companies later joined the band wagon and sold them also. Not a great testimonial for the established grip companies.
In the 1980s and later, tour players started "taping up" their standard (i.e., badly designed, too-thin) grips with gauze and similar materials. Scott Verplank is an exemplar of this. The reason was to "fill the hand", since there were "air pockets" of emptiness where the putter handle and conventional grip held in the palm did not make complete contact between handle and inside of fingers. So good golfers wanted to hold the putter handle in the palm, lining the front top edge of the handle with the life line of the palm, not along the line made by the base of the four fingers where these fingers meet the palm. Again, established grip companies were (and are) doing a terrible job making grips that enhance performance.
Apparently, the Winn, Lamkin, Golf Pride, and other grip companies a) never look at a human hand when designing grips, b) simply perpetuate the thin full-swing grips that were selling last year, and c) do not know the skills and body-knowledge that accompanies good or great putting -- just rather ignorant of how to design a good putting grip that is ergonomically sound for actual golfer hand forms for what works well with good or great putting skill.
The USGA has frankly little idea about putting skill also, and the Rules for putter handles and grips are basically the result of "push me, pull me" influences of grip company pressures and a vague notion of what would be "too helpful" and therefore banned forms. The "pistol grip" form was banned as being, to the USGA rudimentary notions of putting skills, too helpful. But of course the USGA is too unknowledgeable about real putting skill to know that the same rationale would ban fat "super stroke" grips and "flat top" grips and "two thumbs" wide grips as well, with equal force. Alas, we are stuck with the USGA making Rules from the cloudy dark night of their half-knowledge about actual skills.
GOOD GRIP DESIGNS
Good grip designs only started appearing from the usual companies in response to golfers taping up their putter handles. There has not been any change in putting skill or human hands, so this is strictly a "catch up" joining of the band wagon by these artless grip companies.
Good design starts with good skill for human hand form and motion control that promotes good strokes for line and distance. So what is that?
Golfers swing ARMS not putters. In physics, the arms of the golfer are ten times more massive that the putter. That means the hanging of the arms in a NEUTRAL way in gravity avoids unnecessary physics torques that come with odd elbow angles and holding the arms out away from neutral hanging (or even in from this neutrality). Grip makers and putter makes have never known this or used this basic fact to design and sell putters and grips to enhance putting skill. They don't know and don't care and never have so far.
A neutral hanging of the arms is what Loren Roberts and Ben Crenshaw and Steve Stricker all do, and they putt much better than students taught to tuck the elbows in close and the like foolishness. At any rate, these golfers using these arm hangs also have a neutral hand hang off the end of the forearm. The basic human norm is the following, which putter and grip makers have never troubled to notice:
-- Upper arm neutrally hangs vertical in gravity off shoulder joint, aiming arm bones at ankles when erect and at balls of feet when bending forward at address for putting;
-- Lower arm hangs off elbow joint at a slight angle out of vertical, usually about 14-16 degrees aiming the arm bones a bit out from the balls of the feet in a putting forward-bend of the upper torso, pointing about 8-10 inches farther out away from the stance;
-- Hand hangs off end of forearm at wrist joint back into vertical, so the forearm-hand angle mirrors the upper-lower arm angle in the opposite way -- that is, the hand axis (middle of base of palm to end middle finger) angles off the forearm 14-16 degrees.
Of special interest is that when the hand hangs neutrally off the neutrally hanging arm, as is the most frequent state, the mass of the base of the thumb (thumb "pad") folds over the surface of the palm itself, and this chronic folding actually creates the "life line" of the hand, a wrinkle running from the middle of the base of the palm at the wrist diagonally to the outside edge of the base of the index finger. The "life line" of the palm held straight out in front of the face makes an angle with the axis of the forearm that mirrors the angle the forearm hangs off the lower arm. But when the hand hangs neutrally off the lower arm, the "life line" then comes into alignment with the line of the forearm bones.
With this neutral arm and hand hang in the bent-forward putting posture, affording uncomplicated physics for swinging the arms, a mechanically gripped putter handle held in the palms would a) align the upper leading edge of the handle with the life line, and b) be sufficiently ample in radius to fill the golfer's hand without worrisome "air pockets" between handle and inner surface of fingers. ANY putter handle CAN be held so the lead upper edge of the handle fits along the "life line", but no putter manufacturer in the history of golf has ever designed a putter with this skillful-use feature in mind. To do so requires making the LIE ANGLE of the shaft back out of vertical match the HUMAN angle of the forearm and hand in a good-physics posture / neutral hang. Uh, that means LIE ANGLES should usually be 14-16 degrees out of vertical, so 90-14=76, 90-16=74 for STANDARD lie angles of 74-76 degrees. In fact, no putter manufacturer has ever designed and sold such an upright putter, with possible odd exceptions buried in past decades of golf history. "Standard" lies are about 19 degrees out of vertical (90-19=71) -- too flat by 3-5 degrees.
As a result, Ben Crenshaw and Loren Roberts and others may have somehow ended up featuring neutral hanging of the arms, but the putters they are handed are TOO FLAT and there is a mis-match between the forearms and shafts. This being the case, the HANDLE is also mis-matched to the "life line" and the handle sits along the butt of the hand, more in the fingers. This keeps the bad, ignorant grip makers happy with perpetually selling too-thin grips.
Steve Stricker, however, has over the course of 20-25 years of blind trial and error eventually settled upon ACTUALLY aligning his putter handle along his "life line" and ALSO neutrally hanging his arms at address. But because he uses a putter made by an ignorant company, his too-flat putter sits "heel up" at HIS address.
So, the first order of business is to notice that your ignorantly-designed putter promotes a sub-optimal arrangement of handle across the fingers, and this hides the fact that the grip is too thin and the lie too flat.
Okay, unless you bend the lie more upright, the choice is either handle along "life line" and "heel up" or handle along fingers and sole flat to surface at end of putter not also hanging neutrally off arms. Thanks a lot, Titleist, Ping, etc. In any event, grips are too thin for normal human hands.
Today's MID-SIZE grips are usually better for actual golfer hands on putters than are the full-swing standard, too-thin-for-putting grips. Iomic grips came into the market not too many years ago with better radius grips. Winn, Lamkin, Golf Pride et al. started making mid-size grips only in response to golfer demand, not intelligent performance-enhancing company design. But ergonomically speaking, "mid-size" grips are just "normal" and standard grips are just not helpful.
How about "super stroke" exceedingly FAT grips? These are just an unfortunate "fad" that has caught on among skill-lacking golfers hoping to follow a herd into improved results, like the "claw grip" (a weird fix for palsied old men with Parkinsonian dysfunction copied by horrible putters of youth and vigor and then followed in herd fashion by droves of others). These fat grips have nothing to offer to putter face control for line or timing control for distance, and simply appeal to dread-filled golfers worried about hands moving erratically thru impact, when hands don't do anything in putting -- no changes in posture or grip pressure -- if the golfer knows any skill. But the vast majority of golfers, and their swing coaches, know nothing about this.
In addition, these fat grips draw UNDUE attention to the hands, when the attention more skillfully should be in timing and perhaps the arms and the lead thumb. And also, these fat handles add too much mass up top and misbalance the putter, with a tendency to "see saw" the top of the handle inside the hands in the stroke. All bad. Fad is bad!
BAD GRIP FORM
This refers to NOT aligning the handle with the neutrally hanging hand. As noted, bad lies mess this up, except for Steve Stricker's half-solution of "heel up" putter at address. Why he doesn't finish the thought by bending his putter more upright and getting the sole flat in HIS neutrally-hanging arms is a mystery that suggests he doesn't know all that much about putting and sound choices.
Good putting skills features a FLAT putter sole -- one in which the lofted putter conforms to whatever sloped surface the ball sits upon -- ball below feet or ball above feet -- but never "heel up" or "toe up". A lofted putter face (e.g., 3 degrees) held "heel up" misdirects putts to the outside, and one held "toe up" misdirects putts to the inside. These postures also reduce the effective sweetspot and minimize the tolerable variance in ball position and stroke precision in space and time -- all BAD.
So bad lie-angle putters force golfers into bad choices (and they are almost never aware of the problem). Too-flat putters position the mass of the putter head farther out from the feet than a putter shaft that aims the same line as the neutrally hanging forearm. So, the bad choices are: 1) putter handle along "life line" but putter head "heel up" and stroke adversely pushed into compensating paths and manipulations with little room for error; 2) handle in the fingers and putter head too far out, adding unnecessary TORQUE during the stroke tending to droop the putter head inward towards neutral equilibrium in the backstroke, messing up face angle and path and making straight-where-aimed strokes much less likely and inconsistent in any event, or 3) handle along "life line" but forearm now aimed on too-flat shaft so that putter sole sits flat on surface but now arms are held out of neutral with even worse unnecessary torque corrupting stroke for path and face angle. JEESH, thanks, guys!
Strictly ("Stricker-ly") speaking, a good grip form by the golfer is not possible without a matching "good" lie angle. But no one knows this at putter companies or grip companies.
The "pistol grip" in fact, with a bulge off the underside to fill the "air pockets" of the fingers left when a too-thin grip is aligned along the "life line", was deemed illegal by the oh-so-bright boys at the USGA.
BAD GRIP PRESSURE
There is a longstanding CONFLICT in golf lore about grip pressure. During the 1930s and 1940s and 1950s, golfers believed that their "sensitive" hand-eye coordination had to be "exceptional" to perform the "delicate" control of the putter for great putting. Well, perhaps it was useful on "bad" greens with lots of humps and bumps between ball and hole combined with a basic ignorance of what moves what in the human body, but at any rate this "urban myth" feeds into the related "urban myth" that top golfers are also "special" humans with special bodies and "natural" athletic talent not really needing structured teaching or knowledge of skills. These golfers talked about being "safe crackers" and actually sanding their finger tips and soaking their hands in warm water to "up" their putting. Dave Stockton, Jr., appears to still live in this world by teaching that golfers need to "take up needlepoint" to develop superior "hand-eye sensitivity" he thinks is required for putting -- and yet his FATHER taught him to simply swing his arms and hands straight along the line, without any USE of these so-called special finger and hand muscles or parts. Totally meaningless.
The opposite teaching is to "set one grip pressure at address and keep it steady" through the stroke from beginning to end. This camp advises "dead hands" to be used with a pure "shoulder stroke".
ACTUAL grip pressure of real tour players, however, is somewhere in between these extremes. Players have a slight increase in grip pressure at the take-away move and then perhaps some no-change-but-loose grip pressure at the top of the stroke at transition, and then a minor clutching in anticipation of impact. But generally, the variance in grip pressure from start to finish is not too crazy, and is more a "dead hands" sort of pattern. That makes sense, because the fingers and muscles "changing" the fingers and the whole hand turning or flexing by "changing" the wrist angles or even the forearm rotation is the out-dated "old school" way of putting in the 1950s and perhaps 1960s. But on today's good greens, a basic square face moving straight online never involves fingers or wrists or forearm rotations except disadvantageously to correct unnecessary problems.
But the BAD legacy continues today in the widespread teaching and belief that golfers should hold their putters with "very light" grip pressure. Partly this is Sam Snead's fault for coming up with a memorable phrase about the full-swing grip: "hold the handle as if you held a little bird inside your hands". This sort of memorable phrase migrated (unfortunately) to putting, where it immediately married up with the urban myth of "sensitive fingers" and "needlepoint" teaching.
Too-light grip pressure combines horribly with too-flat putters and arms held too much out creating unnecessary torque forcing putters and strokes to droop inward in the backstroke. Strokes made in this situation may indeed be MOVED straight back from address by the golfer's muscles and body parts, but thereafter the inward drooping during the backstroke "looks like" the GOLFER is MOVING the putter on an ARC path to the inside. He isn't -- bad setup and grip pressure is simply allowing the putter to droop or fall feet ward in the backstroke. Golfers and golf teachers ignorant about this physics and the deadly combination of grip pressure and bad-design putters actually think they see a deliberate MOTION made by the golfer on this arcing path. In fact, the stroke is falling out of goodness. But these golfers say "the putting stroke is naturally an arc, and the putting stroke is simply a miniature full swing, and golf is a game of swings on a circle" and the like. In truth, the fact that the stroke "fell down" in the backstroke does not in the least insure that the stroke going forward into impact will MAGICALLY FALL UP exactly as needed to present the putter face back to square orientation just before and thru impact. What actually happens is that the stroke falls out of a good path quite unintentionally and then it is solely up to the golfer to correct this problem coming forward, perhaps hoping to keep track of the arms and hands during the backstroke so that he might (like Hansel and Gretel) follow a decent track coming back to impact. Good luck with that, yo!
So, given the fact that bad-lie, too-flat putters are almost universal, the CORRECT teaching is that the golfer MUST use sufficient grip pressure to PREVENT the in-falling. But of course this correct teaching presumes some knowledge of the physics of good putting of human arms and putters in motion -- right!
The NEXT urban myth that makes for poor and too-light grip pressure is the myth of the "lag". This myth holds that unless the golfer uses a light grip pressure, he cannot sensitively feel and register the "lag" at the top of the backstroke, and then (so the tale runs) he will not have "exquisite touch". Ben Crenshaw teaches this "lag" sensitivity. Loren Roberts also has a very modest "lag" at the top of his backstroke.
Okay, what's this all about? Basically, these golfers erroneously believe that the "lag" is necessary for distance and pace control, but it is not. Accordingly, these golfers are risking loss of putter face control or inconsistent putter face control for no particular real benefit.
A "lag" only occurs when there is a mis-match in the starting or stopping of the hands compared to the movement of the putter head. This mis-match makes the putter handle "see-saw" inside the hands. So in putting there are THREE points in the stroke where a "lag" might occur. 1) at the takeaway, if made with light grip pressure, the hands move but the putter head "lags" and moves a little later, so the handle "see-saws" top-of-handle at rear hand; 2) at the top of the backstroke, if made with light grip pressure, the hands stop but the putter head continues a bit and it's stopping "lags" and then the handle "see saws" the opposite way to press the top of the handle against the palm of the lead hand; and 3) at the top of the follow-thru there may be a similar stopping of the hands before the putter head's stopping "lags" and this "see saws" the top of the handle against the rear palm. A BAD "lag" is when the golfer has "lead-wrist breakdown" before or shortly after impact -- possibly also with a deceleration into impact -- that "flips" the putter head ahead of the hands with the top of the handle pressing back against the rear hand. This last is universally regarded as "bad", but the other three are not.
Is the "lag" at the top of the backstroke necessary for "touch"? No. What is normal for touch is simply good tempo and rhythm with the arms swinging nicely back and thru and the putter mechanically an extension of the arms with sufficient grip pressure. Lags are not possible without too-light grip pressure. But good timing of the arms is always the normal requirement, alone, for "exquisite touch". And that timing does not require the "lag feel", either: If the golfer can TIME the stopping of the hands to generate the "lag," then he doesn't need the "lag" at all -- just the timing, and he has that already.
All the "lag" does for the golfer is risk putter face control, making square online impact more problematic and less likely than otherwise, with no real or necessary benefit. But the "sensitivity" myth lives and breathes here as well, so the teaching persists.
So there are two sensitivity-related teachings promoting light grip pressure.
But the correct teaching is that the same MINIMUM (not less than) grip pressure required mechanically to prevent in-droop during strokes is also enough to avoid "lag" changes of the handle and putter face in the stroke. Swing the arms not the putter.
BAD SKILL KNOWLEDGE
Even if golfers are not explicitly taught or believe that too-light grips and too-flat putters and bad hand form on the handle are "good", they are also taught "bad" patterns that cause funny strokes. One is the teaching that golfers should deliberately direct the path of the putter head on an inside-square-inside arc of this or that specific shape, and also roll the putter face open and then closed in these strokes. Another is that golfers need to favor their "dominant" hand in order to exert "exquisite hand-eye control" during the stroke. Another is to rotate the shoulders horizontally in the stroke changing or shaping the path and / or to rotate the forearms and hands changing the putter face along this arcing path.
Basically, with good sufficient grip pressure mechanically connecting the handle and putter to the body and maintaining the putter face with the thumb pressure on the top of the handle, a "good" stroke is a swinging of the arms straight forward thru impact with a square putter face. There is no role for changing hand muscles or changing wrists or changing forearms.
BAD KNOWLEDGE OF FORWARD-STROKE PRIORITIES
Golfers almost universally have been encouraged to believe that sweetspot "solid" impact is "vital" for good putting. It isn't. And it isn't even very important. What in fact sinks putts is putting exactly and only wherever aimed (for line) with the usual tempo and rhythm. Makeable putts are those inside about 10 feet. Solid impact is desirable, but impact on the toe or heel will still have accurate LINE control if that part of the putter head that meets the ball moves straight down the line with a face that is square and stays square. Too-light grip pressure, of course, combines with off-center impact to twist the face out of square and to deflate the force of impact at a cost of being shorter than planned with the tempo and rhythm. So don't use too-light grip pressure! If the golfer uses the MIIMUM (not less than) grip pressure mechanically required to prevent in-droop, he also has sufficient mechanical connection to persist thru off-center impacts without serious twisting of the putter face off line and the distance may suffer some loss but in the 10-foot range the loss is almost never enough so that the putt actually fails to make it to the front of the lip of the cup.
The priority in the midst of the backstroke and coming forward to impact is NOT sweetspot impact but ANY putter face impact point moved straight with a square face. So what's the conflict? The conflict is that golfers giving priority to sweetspot impact who make any backstroke that droops inward then focus on directing the sweetspot back onto the back of the ball, and not LINE accuracy. The usual result of this is in-to-out stroke paths impacting the ball SOLID but off line to the outside. In contrast, golfers who give priority to SQUARE face moving straight with ANY part of the putter face might make a backstroke too much inside or even looping out away across the line of putt but then simply don't care what part of the putter face meets the ball so long as the arms swing true and straight down the line and the thumb keeps the putter face square.
The final contributor to re-gripping is "funny strokes" to fix "funny reading and aiming". It's the normal thing of almost all golfers to putt this way, reading a putt with low skill and confidence and then aiming poorly into the start line for the poor read then standing at address in doubt trying to manufacture the stroke that fixes this, with some unconscious manipulation of line or speed OTHER THAN simply putting straight wherever aimed with the usual tempo and rhythm.
So that's a MOUTH FULL -- what does it all mean for re-gripping?
If the handle runs along the fingers, make sure the last three fingers engage the handle sufficiently with the minimum grip pressure. Get a mid-size grip, not a fat grip. If the handle and putter lie run along the "life line", get a mid-size grip and press the butt of the thumb down towards the middle and ring fingers with sufficient grip pressure.
What is the mechanically minimum grip pressure? It varies with different putters and different bodies, but any golfer can find it by the following steps I designed:
Flatten the putter sole to the surface, bend the upper torso and hang the arms and hands neutrally and dock with the handle so the handle follows its line thru the hand for good or ill, adopt a too-light grip pressure, "crane up" the upper torso to lift the arms and hands and putter as a unit off the surface to allow the putter to droop inward towards the feet and an equilibrium vertical hanging (because the grip pressure is too little), and then use the lead hand only to progressively add grip pressure in order to "squeeze the putter head and shaft back out to the spot where it had initially sat flat on the ground". At the end of this adding of squeeze, the end result is a grip with a set level of pressure or strength or muscle tone: this is the MIIMUM grip pressure mechanically required by that specific golfer using that setup with that putter -- do it once and learn never to use LESS THAN this grip pressure. Then, no more drooping "arc" strokes and putter faces opening and closing and no more worry about the occasional off-center impact in the makable range.
You write: "I feel the butt end of the grip come up tight against the palm of my left hand at or just prior to the transition." That's the too-loose grip allowing a "lag" at the top of the backstroke. Because you don't "desire" this, it bothers you and provokes a sense of needing to grip tighter before coming into the downstroke. The questionable putter face and LINE control is coming from the too-loose grip that allows the "lag" anyway. You express exactly this by writing: "It's usually very subtle and seems to manifest itself as a tightening of the pinky, index and middle fingers of my left hand but can at times be more widespread than that. I feel the butt end of the grip come up tight against the palm of my left hand at or just prior to the transition and I sense the change in the club's position and grab on tighter, like you would do automatic if you felt somebody trying to pull the club out of your hand." MINIMUM grip pressure prevents all this.
It's unfortunate that conventional / accepted golf causes bad putting skill -- bad putters, bad grips, bad teaching, etc., but one "cure" sorts it all out. There is no point detailing speculatively what exactly happens to result in "not great" line control, other than to know too-little grip pressure is the cause of it all and MINIMUM grip pressure fixes it.
The GOOD THING to learn and perform, with MINIMUM grip pressure, is how to swing your arms straight while this also moves the flat feeling of the thumb print on the handle sideways straight without any twisting or curling off line. Straight sideways swing with putter face square thru impact.
The thumb print IS the same as the putter face aim, so whatever orientation in relation to the body at address and to external space that the thumb print has at address is the SAME that slides sideways thru impact. Learn that and perform that. The end result is focus on the swinging of the arms sideways straight along in front of the body so that the thumb print doesn't twist or curl off line going forward.
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