A significant body of research suggests that most people have difficulty in accurately judging their own performance. For the vast majority of players, even top players, coaching is essential.
A lay lecture about this issue can be seen here. http://www.youtube.com/watch?v=VabtGPVVihA
A lay lecture about this issue can be seen here. http://www.youtube.com/watch?v=VabtGPVVihA