Some rank BYU as being a better undergrad, but those are generally those that put a lot of weight into the quality of the students, as opposed to other factors that actually analyze the institutional side of things. I think I know what you're trying to say, but you're not saying what I think you're trying to say.
And you can just look at the admission numbers to see that the vast majority of BYU students could not get into Yale or Princeton. Some certainly could, but to act like most could is ridiculous and demonstrably false.