We were looking to improve his mechanics, but this doesn’t seem to be the place.
I would worry less about mechanics at this point and focus on being athletic. He shows a lack of intent and does not appear to be incorporating his athleticism into the throw. Get him off the mound and build him up to throwing longer distances. Encourage him to stretch out and throw athletically and with intent to throw hard/far when there is no strike zone to fret over. His body will organize itself to meet the demands placed on it and he will learn to throw more naturally.