I was 13 years old and lived in a very bad place. The only positive was the park and rec league. I did well. One day a HS coach came to me and asked me if I would coach his son's team. They were 10. I have always loved baseball and I said yes. I got books, I listen to any and all things baseball and I coached that team. We were not very good that first year. The HS coach who's son was on that team told me he would buy treats etc. if we won and he wanted his son and the others to have the same enthusiasm I did for the game. The next year, we won our league and won our league every year until I stopped coaching them when they were all seniors in high school. This "rec team" ended up having 8 players who made all conference teams. Oh, one dad was a professional wrestler. He told me that he would take care of anyone who wanted to give me trouble. LOL His son went on to play professionally. (Big strong kid.) I was awarded an award for coaching and my high school coach presented the award to me.
From there, I wanted to be a teacher/coach. I asked to go to a particular high school where the head coach was said to be crazy. He was also a great baseball man. I knew him because he umpired in the summer. He umpired games I played in and games I coached in. I got in and the rest is history. I became a hitting "expert" and he let me run with what I taught. We won a few games by averaging 33 wins a year for 12 years. We won a few state titles. I was asked to coach baseball in the former Soviet Union. I still exchange emails with those guys. I then became a HC and took a program and made it an area power. (Really the players did that.)
The point is if your son wants to coach, learn the game. Teach the game but understand that a coach can never stop learning. I put the word "expert" in quotes because I found through the years that those who think they know it all know very little. I am now an "ex expert." I hope your son gets out of this what he wants. I look at all that I have now and know that I owe so much to baseball and coaching. I am glad that that 13 year old kid didn't run away scared and took on the challenge of becoming a coach.