Following Vance 34's thinking it's not his sucess today but where he's heading. Few high school hitters get away with a long stride ( 1st photo) or significant change in the location of the center of gravity ( 2nd photo). Imho he's close to hitching but that's could be because the (-3?)bat is heavy for him right now. The good news is this is all normal evolution and helping him adapt to faster piching with that darned curve ball will take care of it. Best thing I saw was fast hips, they're critical to a quick swing.