Here's what I noticed:
(1) Pitcher drops noticeably at start of delivery. (Compare top of head to the fence rail in the background.) This creates extra unnecessary movement and directs some energy up and down instead of toward target.
(2) Glove arm is sort of flung to the side and down a bit. It finished low and to the side.
(3) Knee lift appears rather short.
(4) Stride length appears rather short.
(5) Head is out in front of front foot at release. This means pitcher is not in a position to optimally use the body to throw so more stress is put on the arm.
(6) Pitcher falls forward after release.
To fix (1), start with the knees bent more.
To fix (2), focus on getting the glove arm into an opposite and equal position with the throwing arm. This means the upper arms are aligned and the upper arm-to-forearm angles are the same for both arms. As the shoulders rotate, the glove should turn over and remain fixed up and in front of the chest while the chest moves to the glove.
I think (1), (3), (4), (5) and (6) are all related. A lowered stance, a taller knee lift, and a little bit more momentum should stretch out the stride keeping the head over the front foot instead of in front of it. This should let the pitcher better use his body to throw and it should also keep the pitcher from falling forward after release.