the sales increase is not only due to the characters that are in the film it can also be due to audience interest of the producers work, if the audience are familiar with that particular producers work it will encourage them to watch another film they have taken part in.

Although the characters are the main stars in a film, some people have more of an interest in the director because in a large percentage of films directors tend to use new actors and actresses that know one has heard of and this can be a big risk with many audiences.