Receivers don't see a lot of press coverage in high school, therefore the finer aspects and techniques that you would coach a kid on at a more advanced level aren't necessary. Wilson's setup is straight from highschool, and he can get away with it in college a substantial amount of time because he doesn't see a lot of press coverage, particularly in the Pac-12. He'll see less of it in Leach's offense as the WR splits are designed to stretch zones horizontally until it essentially becomes man coverage. That's a staple of all spread offenses with Run-&-Shoot roots.
The fundamental flaw resides in the fact that he has too much weight out over his front leg. Obviously you can't push off with your front leg, you have to push with your back leg. In order to push off with your back leg requires a certain amount of weight on it. The only way to get enough weight on your back leg to push off is to take a false step with it. If your weight is more balanced in your setup, you don't have to take that false step to push off with your back foot.
One of the keys to defeating press coverage is being balanced. You have to bring your back foot up closer to your front foot in order to be balanced. All receivers who have great technique defeating the jam at the LOS start with their feet closer together and in a more balanced position.... that's where it starts. It don't matter what your hands do if you're not balanced when that DB jams you. It's a very subtle aspect.
There's really nothing wrong with being in an exaggerated "crouch" like Wilson is, that's up to the coach. The point is he'll have to bring his back foot up closer to his front foot and be more equally balanced to defeat jams against top DB's.