Others may have a different approach to this but i always find that practicing the movement without the implement always helps. Going through the full range of motion of the throw without the implement and trying to fully extend that arm and finish nice and tall. If the athlete is releasing the shot to early. Work on getting the hip in and under and delaying the 'push'.
Another thing to be cautious of is making sure that the athlete is gaining the height from his legs and not so much his arm.
That's just my two cents but I'm sure others on this forum would have better ideas.