First, the good:
His stride is pretty explosive and he definitely gets a good push off the rubber, so that is great.
2. His hip-to-shoulder separation is pretty good especially considering how young he is.
Next, things to improve:
1. First thing I noticed was his weight goes back as he goes through his leg raise. He should be shifting his weight forward towards the plate as soon as his foot lifts off the ground really. That will allow him a faster delivery, which is always a good thing from the stretch, but more importantly it allows him to transfer a lot more force from his stride into the pitch. Here's a good analysis that demonstrates what I'm talking about near the beginning of the delivery. Has a bunch of other stuff that you can take note of too: https://www.youtube.com/watch?v=SIfEnz1WkBY
- His hand break is pretty early, and he gets to a "fully stretched" position where his throwing arm is up high before his stride touches down. You want the arm to be a little bit later so that it coincides with the front foot touching down. Here's a video to explain this in more detail: https://www.youtube.com/watch?v=Rer9Av4rFYM
Overall, he's looking darn good IMO.