Ok. Back to hitting. Here's a good clip of Brantley exemplifying a no. of things I have explained in detail [on my website and via demos of me doing these things].
1] Stretching the lead side [arm/shoulder/contracting pectoralis/serratus] "against" a "rigid" trunk [ no counter-rotation] and against the stride, i.e., these loading actions are reactions to the center mass moving forward.
2] Note the downward displacement of the head from start to full heel plant. Why? Subtle hip flexion--what I describe as "sitting."
This subtle action helps to facilitate better hip rotation.
3] Note the lead deltoid alignment at foot plant [initiation of the swing].The deltoid is touching the chin. What I refer to as "bury the chin in the deltoid/upper lead arm."
4]Note the upper lead arm and how "tight" [close] to the chest is from initiation to contact. This facilitates a subtle "figure skater effect" of the lead arm.
In that the closeness of the lead arm [distal component] helps to physically link it to the rotation of the shoulders [the more proximal component].
5] The back arm starts and says close to the torso. At contact the back arm flexion angle has NOT extended much. Even though the contact point of the barrel is somewhat in front of the lead leg/foot.
Bottom line: These bat/body alignment components are very consistent with what/how/why I teach what I teach!!
More thoughts on the genetics vs. environment question. Going back [about 20 yrs] to when I first considered working as a hitting instructor. I had a very basic question: Can you actually teach hitters? It was my first question. And why would it not be?
After all, I grew up in an age wherein we learned via what I have described as "disorganized baseball." Meaning that there were ZERO select teams. Nor were their these people called "hitting instructors." Nor was there yr. round baseball.
If for know other reasons [in Tx.] back then no football coach would allow good looking young athletes to NOT play football. HALE No!!
" Back leg is is not the cause but is the effect of other body movement." Of course. And I have done a number of posts here explaining this in some detail, i.e., the "kick back" is a "resultant" that is a function of certain postural/rotational dynamics and also pitch location.
I'll add that the players talking on the clip is a typical ex. of "the action-perception gap", i.e., what you may THINK [verbalize] about your swing is vastly different from what you ACTUALLY are doing to create a high level swing.
As I have said many times as regards hitting expertise there are 3 modes so to speak: "Doing it, understanding it, teaching it." Elite players are--typically--ONLY expert in "doing it."
As a guy who has spent much of my life either trying to create high level movement or trying to teach it, I marvel at the tremendous capability of Simon Biles. I consider it a supreme honor to even watch her!
The very obvious degree of lift she creates in this last phase at the end is tremendous. But note at the start the horizontal displacement [think broad jump].Tremendous physical capability!
One comment in this feed said along the lines of .."she may be the greatest athlete in our lifetime." Not a bad argument in that she can move in ways that NO ONE can actually do at this time.
What exactly does this "getting on plane" actually mean in the context on non-elite level hitters? And what are the exact kinds of joint articulations of the back arm/shoulder are involved?
Based on long experience/observation of non-elite hitters [starting at tee ball], it means the following:
I can still remember [circa the 1970's] seeing the uncontrollable sobbing of some Latin guys getting released at the end of spring training. Never saw any Americans react this way. Why?
Because growing up where they did, they fully well knew the very stark contrast between the opportunities they might have here, vs. where they had been and now had to return to.
In a somewhat relative context, some of my most favorite guys to talk to about this country are cab drivers in big cities like New York. Asking them what they think about this country almost always yields an interesting insight.
As some likely know, I recently talked about some aspects of Ohtani's hip action e.g., hip displacement via eccentric [twisting action] loading causing a "forward by turning," Actions synonymous with "Paul's "pelvic loading." I want to add to what he says here.
I think he is certainly empirically correct in saying that for most elite level hitters, the degree of "separation" between the hip and shoulder rotation [unload] is minimal.
To say it another way, the differential between the hips starting to rotate and the shoulders starting to rotate is minimal. [I will add here that, yes, there is some degree of variability among hitters as regards this differential, e.g, Harper opens the hips more than Trout].