this is what he should improve from my shallow opinions
longer stride distance
when he finish his mechanics, he should stand properly like Greg Maddux with appropriate stride distance
he should learn from Cliff Lee, Tom Glavine to stand properly from where his right food point , instead off-body balance and turn all of his body towards right side of the mound like Johney Cueto and other MLB pitchers
this can be achieve that when Eric Veglahn is about to release his pitch, his body should face and go towards home plate catcher, instead of the force driving by his left arm and go to right side of the mound
Most importantly , no matter how good his stuffs are, in order to be sustainable around 3.5 ERA , 200 innings every seasons, throughout his future MLB career. it should be notice and understand the essence of command his fastball and change-up
For my son it was a very effective change that just dumped into the dirt…lots of swings and misses. Poor kid behind the plate just couldn’t drop and block…he quit playing the next year…went to wrestling and football
In all my many years in this sport I’ve only “seen it” that once and now this kid.