Tom Usher commented or added the following:
This is not new at all. On average, girls have been doing better in the classroom setting and at verbal/written work (as judged by those who put huge stock in these areas and who judge from a verbose and flowery perspective and not always, even rarely, a pragmatic one) at an earlier age than have boys for all of my lifetime and long before. It's common knowledge — has been too for as long as I can remember. Boys catch up later. It's the same with height. Girls grow taller sooner. So what?
Work with what boys are naturally good at, expose them to different academic fields, and encourage them to be as well-rounded as they are able. The content of their characters is most important, not getting precocious grades on "verbal" tests often designed by those with characters too low themselves.