Speed of movement...which means is the pitcher explosive or slow and controlled? Is his tempo slow or fast? Is he like a sprinter getting out of the starting blocks?
Does the pitcher look natural or “over-coached?” Over-coaching appears as slow, robotic and sometimes stiff.
Does the pitcher move from a bent leg to get lower leading with his front hip and does he land on a flexed leg in a straight line toward the plate?
Is the front foot too closed off or angled too much away from home plate? ( I am seeing this a lot on young pitchers) For a RH pitcher his foot is pointed to the third base side of the plate instead being just slightly angled.
Does the pitcher move sideways long enough so that he completes his back leg drive before he lands? Does his back leg get to near full extension just before landing or is it still bent just before landing?
Is his stride length nearing 100% of his height? Short stride kills velocity and add stress to the arm
Is his head positioned between his two feet? (nose over bellybutton) upon landing?
At ball release is his support foot in contact with the ground and is his head and chest positioned out over his landing knee?
Does his entire support foot (heel included) stay in contact with the ground and rubber as long as possible so the weight shifts to the inside of the entire support foot while the foot drags down the mound surface?
Does he land with his weight on the middle to inside of his landing foot or is he falling off to one side or the other? Is he front knee positioned over his ankle? This is his foundation for transferring all the forces you want to get to the ball. If this is weak velocity and control is reduced and stress goes to the arm.
Does he take the ball out of the glove with fingers thumb up swinging the hand down, back and up into the cocked position as late as possible? (or is he lifting the ball up using his elbows? WRONG) Does his throwing arm get back into a natural but fully extended position?
Does he break his hands late...after his lead foot is down and his head and front hip have started to move away from the rubber?
Does he brace-up his ankle and knee and hip so that upon landing his hip acts as the axis of rotation for his upper body?
Does he have good upright posture moving from the back leg to the front leg?
Has he removed all slow movement, hesitation and lateral (side-to-side) movement from his delivery including bending forward, leaning backwards or swinging the leg out and around?
At ball release is the pitcher’s head and chest positioned in line with our better yet out over his landing knee. (if his head is behind his landing knee this indicates he is not creating enough forward momentum)
Does the pitcher finish with his trunk powerfully flexed forward to a flat back position? Other things to consider. Do the hands work together and sync up with the body. Thus why I like the hands moving up with the leg out of the wind-up and the hands positioned high on the chest to move down out of the stretch. Stationary hands do not allow good rhythm or timing. Get the hands moving.
Fix what the legs and feet are doing first. This is where weI start. If the foundation is weak the delivery will be weak and the arm will get sore.
This list may seem complicated but it is not. The key is how the pitcher starts which effects how he finishes. Fix the beginning by helping him understand that it is the body that produces velocity…not the arm.