Being tall, long AND athletic might get them a high rating if they can demonstrate strong rebounding ability & defense. They can't be a total project. That is Sissoko — & to a lesser extent, Atiki (who has a better feel for defensive footwork & hand placement than many on here are giving him credit for; some of that he surely came to BYU with, having learned it in academy play in Canada).
As for Isaac J, he doesn't have the athletic ceiling of Sissoko or Atiki, but he's definitely an above-average athlete for a 7 footer, & is relatively long & big-handed like his lil bro. He doesn't have the optimal lower strength for a 5, but he'd got the sheer height & length to compensate for it, whatever level of ball he might end up at. He also has good overall bball skills. For those reasons he was a top-100 recruit coming out. As was a more raw Sissoko.