Well it looks like the debate has already happened and it turned out to be an asynchronous one on separate websites that is a good example of how not to use the internet.
Hitting is a tough area to discuss.Ideally such a debate would include both (for simplicity's sake,2 sides would be nice) parties understanding the others position well enough to summarize it to the others satisfaction,then areas of disagreement coule be identified as well as areas of agreement.Language could be agreed on and questions constructed and answered or approaches to develop an answer could be identified.Sometimes it is a lot harder to find the right question than the right answer.
Of course,this did not happen and the "dialog" degenerated rather rapidly.In general, I find that Jack remains reasonable,and open to criticism without getting too defensive.Paul tends to take a polemical attitude which can be very alienating and off putting,but he nonetheless has worthwhile ideas.I would still take the opportunity to read through his stuff for valuable ideas.Don't throw the baby out with the bathwater regardless of how irritating you may find it reading through Paul's stuff.Here is a summary of my interpretation of his recent scap loading/response to Batspeed posts.Paul is welcome to correct this.
Paul reiterated the importance of distinguishing between cues and reality and between form and function.This is a useful thing to keep in mind,however,there is almost always going to be overlap and ultimate reality is never fully describable.
Nyman gives credit to Jack for pointing out the necessity of the arcing handpath,but believes this is whip rather than torque.
Nyman thinks that bottom hand torque and top hand torque could be cues but are not physical reality.He uses a somewhat reductio ad absurbum demonstration of a thought experiment where the dismembered hands would demonstrate no torque if there were no significant batmass/inertia to force them to react.This shows a lack of familiarity with Jack's material.The torque vs whip debate would be a good one to hear them have,but that seems unlikely.Jack has said (correct me if my memory is faulty) that the hands are driven by arm connection to the shoulders while emphasizing that arm action must avoid disconnection such as by extension.Paul then uses this to totally dismiss Jack's ideas about bat movement.
I would even say that perhaps Paul and Jack both think that actions at the shoulder complex are what move the bat.
I still think Jack's bat movement ideas are important.There does seem to be an essential detail of swing mechanics that results in the bat accelerating into the swing plane as described by Jack.This acceleration seems to be related to a push/pull action of the shoulders that transmits though the arms and hands to the bat.Jack thinks this is torque.Paul does not.Nonetheless,the bat is turning and in a way that seems related to both hands applying force.There may be some important questions here.Is this an important part of what Nyman calls mass-inertia transformer step-up or changing moment of inertia of the bat-arms-hands linkage/connection to the torque of the torso ?
Is it important to turn the bathead about a center of rotation that approaches the knob of the bat as body coil is finishing?
Does turning the bathead back toward the catcher assist in keeping the torso/hands back ?
Is it important that the bathead not extend too early either by wrist snapping/adduction/ulnar deviation or by overshooting the swing plane perpendicular to the torso?
Nyman points out the usefulness of comparing the throwing motion to the hitting motion as well as the necessity of describing various joint motions.He illustrates some of these motions well,but does not adequately explain some of them and also leaves out the essential relation of the shoulder motion to arm motion,especially internal and external rotation of the arms.This is an area where I am a "splitter" rather than a "lumper" because these details are crucial to good loading/avoidance of disconnection/enabling of optimal bat motion.As much as you may have distaste for these details,I would urge you not to dismiss them just because Paul stresses some of them.This was a major contribution of Jeff Hodge who is also very knowledgeable about biomechanics(Hodge did not appreciate scapula horizontal adduction,however).I would even go so far as to say this info can reconcile to a great degree the supposed differences between what Jack and Paul describe.
Nyman also prints some of Ferroli's stuff and critiques Ferroli and Epstein as well.I find that if you have a reasonable swing model,the descriptions and cues of other authors can often be very useful.Ferroli's excerpt describes the motions early in loading of a no-stride swing.he describes 2 phases(similar to what Paul has described as a "2 piece load" in the setpro public hitting forum archives) which fit with what I have described on this site and elsewhere.From an arm action perspective,the first action is lead by the internal rotation of the back arm.The second phase of loading which Ferroli calls the "stretch" corresponds to scap loading.I find that while the shoulder joint has 3 degrees of freedom (humerus in shoulder socket) as does the scapula (moves shoulder socket)there is still limited motion in the shoulder complex because of the ways the arm and shoulder motions blend.In other words,you can get a "shoulder bind" (just as you can get the "wrist bind" that jack describes based on wrist action and grip).You must internally rotate the arm to then permit adequate pinching of the scapula so loading is not interrupted and the bat can turn efficiently into the swing plane (this is an important fault/flaw in the John Cronin hitting clip Paul uses to show what he interprets as THT in a disconnected swing).In my opinion there are a number of these anatomical motions you might as well go ahead and learn.Once you do,you can see how the scap loading/"dynamic horizontal aduction" of the scapula is limited when the arm is externally rotated as opposed to internally rotated.Once understood this can be taught just as Hodge does in throwing.The same summation of motion is a key to keeping the front shoulder from flying open in throwing.In both hitting and throwing the avoidance of a shoulder bind is necessary to avoid interfering with the last bit of rapid coiling which Paul desfribes as a "cusp" and which is described as "xfactor stretch" in the downswing in golf.You need to coil and uncoil well and the bat/club motion has to accelerate compatibly into the developing swing plane so the loading unloading sequence is optimized.
Paul also is unwilling to acknowledge the usefulness of Epstein's "counterrotation" cue.Again I think Epstein's description is very accurate and useful.The back scap continues to load as the hips open to rotate into toe touch.This is the feeling of winding the rubber band and describing it as counter-rotation does not have to doom one to taking a big back swing.This is just like Hank Aaron's description of "coiling without taking a big backswing".
Paul's description of scap loading as an attempt to go from form to function is a good one.Motion wise,he equates it with dynamic/rapid/uninterrupted horizontal adduction of the back scapula(pinching).I would describe this as an important factor in getting good full loading of the torso/body twist permitting a good "xfactor stretch" or eccentric to concentric muscle action with an efficient reversal "cusp" as he describes it.This can create more power by better xfactor stretch and connection IF the bat and top hand motion as described by Jack(which I think of as not just form but a marker of good function)is also present.
Paul also restates his description of how the front scap abducts as the back scapula adducts to permit loading without a backswing,but he seems to use counterrotation to mean backswing as opposed to Epstein who thinks of counterrotation as the lower body hips opening as the hands/torso stay back.
Paul also muses that hand torque would have to be applied by wrist snap/wrist adduction/ulnar deviation of the wrists.This is not how Jack describes the push pull shoulder action that the arms/hands transmit to the bat.Is there torque ? If not what is it ? It would be nice to hear a reasonable give and take between parties.This does not appear in the offing.Neither does Jack recommend "radial deviation" which is probably just a way of delaying adduction so the bathead does not extend or overshoot the swing plane early.Jack describes the grip/wrist action/avoidance of wrist bind well.
As for the pictures,Pujols also is concerned about the front shoulder flying open as in throwing.I would say the proper arm action with internal rotation of the lead arm elevating the front elbow is a necessary part of this shoulder action as it is in throwing and in loading the back scap properly.
I would say that Arod does use bat motion that is what Jack describes as prelaunch tht and tht at launch,but that is a personal interpretation.
Paul also asks why so many mlb hitters are rotational when coaching isn't.I would say that if you aren't rotational,your mechanics prevent you from surviving.And the number of insructors that do teach weight shift THEN rotation with connection until contact is extremely small.So,the hitters must not be doing what they are taught or what they think they are doing.That would not be terribly surprising.
With regard to describing joint terms (arhtrology part of kinesiology),Nyman's pictures are useful.This list may/may not help,but I would encourage the coach to meet with their local kinesiology type and look at a skeleton while trying things out on your own body.
It helps to think about whether you are describing motion of the scapula/arm/forearm or wrist as you name terms.The arm flex/extends,abducts/adducts and/or internally externally rotates in the shoulder socket(3 degrees of freedom).
The scapula elevates(shrugs)/lowers,retracts(horizontally adducts-pinches)/protrudes(horizontally abducts),or rotaesup/down(3degrees of freedom).Shrug is probably not the most accurate way to describe the horizontal adduction of the lead scap to assist in hooking the handpath during unloading.The action is leass elevation/more pinching/horizontal adduction.
The scapula does not turn in the transverse plane with an axis through the humeral head.Horizontal(transverse) adduction/abduction happen about an axis(longitudinal/saggital/paramedian) closer to the spine also involving the collarbone joints,etc.
The elbow has 2 degrees of freedom,flexion/extension and pronation/supination(twist) of the forearm.
The wrist is very complex.I would think of wrist snap as both wrists adducting/deviating toward ulna bone in forearm.The opposite of this would be radial deviation.
Wrist roll is a result primarily of forearm twist,either pronation or supination.
If you think that can be complex,it's notihing compared to hip and spine.
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