WWI Military Leadership?

I have been thinking about the question of military leadership in WWI. It seems it is generally believed that the leadership in WWI was very bad. Why is this so? I think perhaps it is because of the lack of large scale wars in the 19th century, as well as new weapons, which the military leaders may have been unfamiliar with, underestimated, etc. But then again, there always seem to be generals who pop up throughout history who can take advantage of new weapons. Maybe there were none during WWI, but now I am back where I started: why is this so?? I am interested in anyone's thoughts.