Off speed works great for the "killing of batters" because kids don't load and stride to balance early enough. They must learn to separate the stride from the launch by a moment in time. Most don't get their hands back by shoulder rotation so when their foot finally gets down they have nothing to hit with and they continue to drift forward seeking some tension/torque.
The lead elbow must be behind the belly button at toe touch. If you have filmed him he would have been 0 for 4 on that criteria.I don't have to see the game to know that.
Easy fix..use a Hands Back Hitter
www.swingbuster.com that is why it was built. It has helped a lot of kids learn and Dads teach torque which is creating and maintaining the shoulder load until toe touch. There IS more to hitting but until they learn this the rest has little relevance