Historically, kids in Utah got recruited by schools in Utah and that was about it. When BYU was the best year the state, they got the pick of the list with in-state (and LDS) kids.
Over the last 10+ years teams from outside of Utah have increasingly started to recruit here and aren’t scared away by missions. Stanford, Washington, USC, Wisconsin, Alabama, etc have al pulled kids that historically would have played in Utah.
Add to that Utah’s move to the PAC12 and there are a handful of kids that get lost to Salt Lake that used to come to BYU and the Harris in recruiting are almost entirely explained.
In the 70’s we picked up a guy by the name of Jim McMahon because he literally didn’t have any other options (anyone think Jimmy Mac is at BYU if someone else would have come calling?). Today we can’t even pick up a legacy kid in our backyard like Covey.
The College football environment has changed radically over the last couple of decades and none of those changes have been in BYU’s favor.