Research is clear that when parents and teachers work together a child tends to do better in school.
There is no reason to think that it is any different in youth sports. The coach has made a commitment that involves many, many hours of preparation beyond the hours spent at practices and games. Try to remember this whenever something goes awry during the season. To the extent that you can do so, ask if there is any way you can help. By getting to know the coach early and establishing a positive relationship, it will bemuch easier to talk with her later if a problem arises.