Austin, I think he might have included the loss of role model in the fifth factor.
I'm sure I'm biased by the fact that I have two sons-- one of whom is PG and about to flunk first grade-- but when I look around, I see this everywhere. In my niece and nephews-- nephews all struggling, niece doing great. In my teenage stepchildren-- 16 yo stepson, who took the SAT in 7th grade and got a DYS-qualifying score but is going to barely graduate from high school and hopes to become a tattoo artist; while his 14yo sister, not as "naturally bright," is absolutely thriving and dreaming of big things. In my younger first cousins, now in their 20's-- boys all barely graduated from high school and, not knowing what to do with themselves, joined the military-- girls professionally achieving great things, their only problem (according to them) that they can't find a decent, solvent, independent guy.
In my son's classroom, only the boys are struggling, and half of them are medicated.
Totally unscientific sample, obviously, but it does make me wonder what is happening...
Not to take away from the difficulties of girls... I was one... still am... and a feminist too. As a gifted girl, school was a haven for me... the real world was another matter!