Yes, BYU has beaten two ranked teams. They're no longer ranked because they lost to BYU... That's kind of how it works. You lose, you drop out at this time of year.
ASU would potentially be ranked ~15 if they had won the game. Utah did lose a close one to SDSU, but who knows how the rivalry game affected them. It's not unreasonable to think they might be ranked still had they won.