How one connects to the cue will be associated with how the cue moves. In the snooker video teaching the grip with the hand feathering open on the back swing the purpose is to keep the butt end from raising up which causes the tip to go down at the other end of the cue.
When that raising happens on the backswing it must be reversed on the forward swing to return the cue to a more 'level' position or the result is that one hits down on the ball more than as was probably intended. For a 'full pendulum swing', the butt goes up & the tip goes down & the reverse is true too.
There is a video by the Oyster guy that shows one of his young students trying to use a full pendulum type stroke that does just that. He basically swings the hand up but then does not swing it back down but instead goes AT the cue ball with the hand which changes the approach angle significantly from how it was at the set up position. Basically he pushed when he should have pulled. I think that tells me that perhaps his mindset may not be conducive to using a full pendulum swing, BUT...that is what he was being taught.
Everyone does not use a full pendulum swing & hence how everyone connects to the cue is different & how that connection changes during the stroke is different.
The same can be said for the wrist along with how it's movements coincide with what the elbow may or may not be doing.
That is why I do not agree with the fixed elbow theory & that it makes things more simple. To me, that is simply not true. IMO keeping the elbow fixed necessitates other compensatory movements in the wrist &/or hand/fingers that to me, sort of go against the norm of our bodies 'design' & composition & maybe even our thought process. That is unless one completely takes the hand & wrist also out of function but doing that increases the up & down aching path of the cue tip.
IMO, if one wants simplicity, then simply move the cue in a straight line because it is a straight implement & we should be using it on a straight plane in all directions & not swinging it on the arc of a pendulum rod.
I think when some significant boimechanical studies are done that will be the conclusion.
The human body is not a simple machine & to try to make it function as one is counterintuitive, at least to me.
To me, the more simple common sense approach is simply to let the body do what it needs to do, so that it can be as effective as it can be for the task that we are asking it to accomplish. That way one's mind is much more free to play the game & does not have thoughts in the back of the mind or doubts from our subconscious or it even being upset because of the limits that we are putting on the body that it has available to use for the task that we are asking it to help accomplish.
Does one want their subconscious mind's focus to be on keeping one's elbow fixed or does one want one's subconscious focus to be on playing the game, pocketing balls & getting position.
A pendulum is very simple to explain & teach. It swings up, down, & up again. Since it is simple, it is easy to see any diversion from it's simplicity.
However... put a long stick at the bottom & issues regarding the moving of the stick & especially the tip end, in a straight line should become vividly apparent.
Picture a baseball bat being held at the nob & being swung as a pendulum. Then picture it being swung with a pool cue stuck on the barrel end of it & trying to keep it moving level & straight to hit a ball precisely with a tip on the end. That should make the compensatory movements or disconnection need issues apparent.
I true pendulum has only the one pivot point at the top. A human arm has a shoulder, elbow, wrist, 3 joints on each finger & then a relatively loose connection to the cue. That does not resemble a simple rigid stiff pendulum rod & to try to make it as such is simply not a logical decision to me.
One can either use the natural dexterity that we have or one can try to inhibit it. To me, inhibiting it is not natural . To go against what is natural is very often not the best thing to do.
There are heel & center shafted putters. They should be 'swung' or stroked differently due to that fact. When one swings a center shafted putter as a heel shafted putter should be used, one is fighting the design of the implement. Why do that? If that is how one wants to putt then one should get a heel shafted putter.
A pool cue is straight & we use the end point of it. IMO it should be used straightly.
We simply do not have the option to get a differently shaped cue stick.
The point of all this is that all too often comments are made seemingly with the assumption that we all are using the same 'full pendulum' type swing & I would certainly think that all of us are not. I know I am not.
So... any & all comments that are not first qualified should be taken with perhaps many grains of salt, as the comment may not be a fit for some of us & may not even be a fit for the individual to whom the comments are directed.
Perhaps no question should be answered without first asking the one asking the question, 'What type stroke are you using?'. Maybe no question should be asked without first declaring what type stroke one is trying to use.
The problem with that is that many do not really know what they are actually doing & perhaps only know what they are trying to do.. Their proper declaration or answer should probably be, 'Well, I'm trying to use XYZ.'.
So the bottom line is...my wrist action may not be your wrist action & my wrist action may not be good for you or your stroke because I'm not focusing on keeping my elbow fixed at a point in space. I am simply moving the cue straight along it's natural design nature. Sometimes that means releasing with the front fingers & supporting or catching with the back fingers. Fran Crimi, I think, has settled on actually playing with the last 2 or 3 fingers as her primary connection to the cue. I tried that & it works quite well but is very uncomfortable for me as I have played much sports & using my thumbs & forefingers are very common & comfortable to me.
IMHO, The stroking of a pool cue, please note that I did not say the 'swinging' of a pool cue, when what actually goes on is analysed I think it will be found to be a bit of complex biomechanical operation. However... it can be done seemingly effortlessly. That's because the human mind & body & the connection between them are amazing.
Sorry for the rather long rant but one point hinges on another much the way our hands & arms have multiple 'hinges'.
Best 2 All,
Rick
PS Jack Nicklaus did not move the putter exactly that same as he moved his other clubs because they are intended to hit the ball into the air while the putter is intended to roll the ball on the ground. Many golfers use their putter much the same as they swing their other clubs. IMO that is a mistake.