Based on that criteria, BYU deserves to be ahead of Clemson. Beating Arizona, ASU, and Utah is significantly more than Clemson has done.
But not everyone agrees with me. Lots of people think it's better to rank teams based on which team you think would win on a neutral field. If you rank teams that way, I can understand ranking Clemson ahead of BYU. I personally don't like that ranking system, because it relies too much on guessing about things like "eye test" and "intangibles" and "potential" and stuff like that, instead of record, but if you are using it to rank teams, you can defend putting Clemson ahead of BYU.