Goosegg says it all. Keep in mind that every player will go through a slump. During this time some players will begin to doubt their tools or approach, things that got them there in the first place. Continue making solid contact and those balls will start to fall once again. It is a long, grueling season of ball and there will be more opportunities to get on track. My son during his first year of minors went through 2 slumps over 4 levels. Both times I never brought it up when speaking with him, he knows what is happening. Many times we didn't even talk about baseball. I was a nervous wreck each time he stepped to the plate, but kept it inside. He will figure it out without undue pressure from the gallery. Now I look at it as a test how long it will take him to figure it out. You as a parent have done all you can teaching him the game. By now he most likely knows way more than you anyways. Enjoy these exciting times for him, he is learning how to be a man, a professional baseball player. Trust in the process.