As I have said before, when I was growing up in Pasadena/South Houston Tx. , if you were caught playing golf or soccer on a field, you greatly increased your chances of getting your ass kicked. Baseball was ok as being sufficiently masculine one could say.
And as regards someone approximating my physical stature, football was essentially mandatory, i.e., "son, with your body you HAVE to play football." And I did.
But yrs. later, in my pursuit of trying to understand how the body works in the context of swinging a bat, I found any number of golf instructors that I thought had a MUCH better understanding how humans swing an object [any object really] compared to most baseball instructors.
I ended up buying at least 10 bks. on golf biomechanics, and I spent a considerable amount of time watching instructors teach on the golf channel.
This process goes back to over 15 yrs. ago, and I will say that this investigation into golf instruction WAS helpful [I recently mentioned the retired physician Jeff Mann and his very thoughtful/thorough info].
All that is to say this: If I had a son or daughter that I wanted to help to develop a good baseball/softball swing, I would very much encourage learning to swing a golf club.
I'll add a good ex. of a young guy [3 yrs. old] who is looking pretty damn good at creating the basic "tilt and turn" unloading that I advocate/teach.
I have seen over the last 10 or so yrs. a high degree of focus on the back leg and/or the back hip action as being THE KEY to creating very good hip rotation. This [of course] typically entails NOT any kind of rigorous argument of biomechanics or physiology.
No. It's simply an assertion along the lines of....."see...see this...THIS clip PROVES my assertion!!"
Well, yes. I do see the clip. And I do hear your assertion. But. You have not really convinced me.
I'm not at all convinced that ONE leg or ONE hip is THE causal link to high level hip rotation.
Though most know me as a teacher of hitting, the fact is that I have worked with many pitchers and position players regards developing greater THROWING capabilities. The overarching [big picture] theme is predicated on the idea of optimizing muscular tension of the trunk region.
The trunk is defined as the musculature of the pelvic region, mid trunk, upper trunk [scapular complex]. Optimizing both the eccentric [loading] and concentric [unloading or "turn around"]
This, of course, entails numerous considerations as regards the magnitude, timing, and direction of many muscles and/or muscle systems of the trunk.
Anyone who is familiar with my teachings knows that I am pretty thorough and pretty detailed oriented [a process 20 yrs. in the making]. Any newcomers are subjected to a basic process as regards the first time they hit with me.
The process works as follows: I very much understand what I refer to as the "high standard." And I know the process by which individuals go about the process of developing/working effectively towards that high standard.
I also very much know that both parents [typically dads] and players either think or have heard many things about "how the body works" as regards high level hitters. Many of these things are simply false.
Over the yrs. I have had the great fortune of meeting dads who really wanted to learn how to help their sons or daughters reach their hitting potential. One such individual is Stu Byrne.
An engineer by profession, he did a remarkable job of using his engineering eye to learn "my stuff." He had a remarkable way of taking my words and creating DAMN GOOD! visual interpretations.
He created MANY clips--including quite a few still sequence clips which many on my site really liked:
Note that at set-up the head is behind the knees. But by foot plant, the head moved away from the knees [and towards the plate]. Like what happens in a stiff-legged dead lift ,ie., hips are pushed back/head and upper trunk react by going the opposite direction.
This, of course, starts to set-up the swing plane and it serves to create eccentric/isometric tension in the posterior chain [hips, erectors--lower back--and back leg musculature].
Most familiar with my teaching, know that I emphasize --and have numerous drills/exercises forcing this--keeping the upper lead arm very tight to the body. The reasons for this mandate are both biomechanical/physiological and empirical [observing elite hitters].
An example of the latter is this clip of Prince Fielder:
Go to 12:22 [and slow it down even further via .25 setting]
This is a terrific example of what I refer to as keeping the upper lead arm very "tight" to the body.