12 yr old pitching help

My 12yr old son is having a problem with bringing his back foot off the ground before he releases the ball. Any help with would greatly be appreciated.

Cold be due to a number of differnt reasons. Poor posture as in getting the head and shoulders ahead of the hips could cause it. Early shoulder rotation caused by posture or glove issues could cause it. A lack of srength in the low back to keep the trunk upright longer could cause it. Or any combination of theseā€¦