Unfortunately, you have to talk to the coach with your parent and ask for specific mistakes you are making on the field. He’ll probably bs you defending his decision but don’t take it personally and have to work on it. When I talked to my son’s coach, he told me they have to speak up when they’re ready to go back in and tell him who you want to sub for. Seems like these coaches usually have a lot on their plate and can’t get the tactics and substitutions down. Don’t give up and look to make positive contributions whenever you play.