Thoughts on the back leg kick in the pitching follow through. Do we feel the higher the back leg kick is the better for velocity, should that be a focal point in teaching pitching mechanics if so drills to assist in getting that back leg a little higher.
It has been my experience that the back leg acts as a balance component within the overall choreography of a pitcher’s delivery. Others may have had, or use, their back leg kick, push-stretch and so forth for other reasons.
In any event, I have found that those pitchers that get a tremendous stride and body motion forward in their final stages of delivery and release, do so with the ending body being balanced off at the pelvis with the upper body being counter balanced off with the back (pivot) leg. See the picture below please.
How the back foot finishes is a result of things that happen earlier in the delivery. As such, it might be useful as an indicator of those earlier things but it is a non-teach.
Also, be aware that, in general, the back foot will come around in a path that mimics arm slot. So, an over-the-top guy’s back foot will come more up and over while a sidearmer’s back foot will come more out and around. Don’t try to force all pitchers’ back feet to come up and over.
What Roger mentioned is good advice.
In addition, any and all movements by a pitcher is very personal and dependent on the physique of said pitcher(s). Your tall and slender pitchers will have a noticeable difference compared to stocky, muscular, and compacts. Add to that, aggressive pitchers in the drive forward can be very animated with their lower half compared to the pause-n-drive style of pitcher.
I mention all this based on mature, fully developed athletes - not youth or even high school varsity youngsters.
On this web site there are videos of many different professionals and their individual persuasions with regards to your question. Study some of these people and you’ll see common traits - but, if you look closely enough you’ll notice little things that repeat themselves. In fact, all pitchers will in latter innings, depend more and more on these little things, or traits if you will, to see them though. So you might be looking at a higher kick by the back leg - or lower, a quicker knee lift or slower, so on and so forth.
By the way, your question is a darn good one, if you plan to be a pitching coach some day. I say this because when a pitcher is going through a period of difficultly, a pitching coach will watch hours and hours of a man’s appearances and pick out the things that change, even in the slightest. Sprains and strains, endurance deficiencies, lack of stamina, and the like are all signs worth looking for. Also, a change in form and routine - even in the slightest can be signs that a pitcher is trying very hard to reinvent himself.
I know my comments went way beyond your basic question, but your question was a good one for other things.
Thank you for the compliment. I know that pitching is somewhat of a science and to be good much less great there has to be dedication and a knowledge of every aspect of it. It’s good to be able to pose a well thought out question or topic and receive legitimate answers on here. Thanks for all of your replies on my topics, it’s appreciated.
Your son currently uses that back leg to balance himself off with his forward motion and his ending posture. So, number #1 show exactly the ending posture of your son’s head into the pitch and notice the ending position of his foot - nearly equal at the opposite end of his body where his head is. This is very common with pitchers who have a back leg kick that’s animated with their delivery. The human body will automatically balance itself off like this, ten times out of ten with a physically fit athlete.
If your son can get his head down more and more forward with an aggressive drive, his stride foot will plant better than being on the biting edge of the outside of his stride foot - see #3. He’ll also balance himself off better with a back leg kick that’s stretched out more - see # 2.
Ending upright like he is, is not all that bad though. He looks strong and in command of what he’s doing. On the other hand, try my suggestions, a bit slow in the beginning and watch his incoming pitches (fastballs) seem to “sail” in without much effort on his part. Then after he’s wormed up and into the grove of things, crank up the intensity and the aggressiveness of his drive forward with the delivery phase(s), and watch a better control of his fastball, a sharper bite on his breaking stuff and a better looking pitching motion overall.
Your son looks very strong and should have a good tolerance level for his inventory of pitches.