At the risk of making a few enemies, lol, take it from a team that has played both: CC is the better/tougher opponent, and not really close. No one saw this coming from them, but it is what is.
It's really tough to apply the transitive property in football, especially a few months apart. That said, having watched both the week 1 game and the CC vs BYU game, I don't think you can say that CC looks better than ISU right now. And
that is not even close. That CC/BYU game was sloppy AF on both sides.
The week 1 game is the outlier of ISU's season, without a doubt. I think it's fair to say that most ISU fans have been skeptical all season because of the loss to UL, but these last 3 weeks prove that it was the outlier (not the middle of the season wins).
The only way I see your statement being remotely true is if the CC/BYU game was a huge outlier for CC's team. And even then, I don't see how you could confidently say CC >>> ISU, at best you could say that they're close.