One thing I had to understand after coaching youth football for close to a decade that watching your kid perform is an extremely vulnerable situation for parents. Most people regardless how hard they try will never truly be objective about their kids. You have to take it with a grain of salt.
Those kind of emails always bothered me. I never judged myself by wins or losses per say. It was more about development of the kids for me and them having a positive experience and wanting to return to the program next year. I was more bothered by the kids that didn't return which was a small minority than the kids that returned every year and still playing to this day. I was out having a dinner with my family and happened to be seated next to a family of a former player. I didn't know it at the time but the kid had some developmental issues. Extremely quiet then and still to this day. Undersized but explosive and one of the most aggressive kids on the team. His mother approached me about him wanting "to do other things" which is always code for being a running back. I had 7 kids that were more suited for that than him. But none of them were as strong or aggressive on the defensive line. Mom basically told me the kid dam near suffered from PTSD from being on the defensive line and was overjoyed when he found a coach that allowed him to be a skill player. Messed up my whole meal. Still happy for him. Had he continued to play with me more than likely it would have been that way for a minute because it would have been the same kids on the team.
You have to do what is in the best interest for your team. Parents will always have to do what is in the best interest of their child. Today that probably means finding him a team where kids aren't as talented that will allow him to be featured. It used to mean having a determined spirit, putting in the work in the off season and showing the coach you now deserve those opportunities. Coaches, 9 times out of 10, will play the kids they believe give them the best chance to win. If that happens to be your child, he will play.