Even with TJ, I’d guess not all the “top” students in the area attend there. Many kids just don’t want to leave their home school to go to a magnet. There may be other Northern Virginia schools that are having better success than your school, OP in having their kids go to “top schools” for whatever reason. Also, some of the other Northern Virginia schools may be more inclined to have kids that are just as happy to attend UVa, Wm & M, or Virginia Tech and less kids even aiming for or applying to “top schools.” TJ may be attracting the most competitive kids and families that aim for Ivy League, MIT, etc. to begin with. But that is just a guess on what else may be at play.