MoR canon points out itself that Ravenclaws aren’t necessarily the cleverest, they’re selected mainly for the virtue of scholarship and curiosity.
Dumbledore was a Gryffindor, and Riddle and Snape, and in the present generation, Draco, are all Slytherins, and they certainly don’t seem like they could be outside the top quartile.
MoR canon points out itself that Ravenclaws aren’t necessarily the cleverest, they’re selected mainly for the virtue of scholarship and curiosity.
Dumbledore was a Gryffindor, and Riddle and Snape, and in the present generation, Draco, are all Slytherins, and they certainly don’t seem like they could be outside the top quartile.