It is no secret that BYU Sports in general are much better than the BYU Football and Men's Basketball team.
Women's Soccer, Volleyball, Softball, Cross Country, Track and Field, Basketball and Men's Cross Country, Volleyball, Track and Field and Golf are consistently ranked high in the National Rankings. The Cougarettes, Men's and Women's Rugby and Badminton teams are also ranked really high. All these good teams make BYU appear to be a really good athletic school.
In fact, BYU Sports are really good with an exception to football and men's basketball and a very select few Olympic sports. While it is understandable that the Cougars wouldn't dominate in every sport, they do consistently win in 13 out of the 21 sports. By consistently win I mean that they are either the conference champion or runner up just about every season.
It is odd that out of the eight teams that seem to struggle, two of them are the most followed programs, football and men's basketball. Football had its glory days in the 1970-1990's but since then with a short stretch in the late 2000's the team has been average. The basketball team has been historically average as well with a few great teams sprinkled in from time to time. While there are many reasons why this is it comes down to three things: Money, Exposure and the Internet.
Money
While this is the most obvious reason, but there are some aspects that are often overlooked. Recruiting is the obvious first reason. BYU coaches can only make so many long distance trips and bring in so many out of state players on their budget unlike some other schools that have more resources.
Facilities are huge as well. The Indoor Practice Facility is nice and better than most G5 practice facilities around the country, but quite honestly, it is nothing compared to some programs. The University of Arkansas, a team who hasn't been good for a long time, has a full size replica indoor field as well as one and half outdoor practice fields that are also replica to the stadium. The basketball facilities are just as nice featuring a huge weight room, two full size replica basketball courts and plenty of lounge area.
When players see that, they love it and the humid Indoor Practice Facility with the constant buzzing is not as attractive as other locations. The Marriott Center Annex was a huge step in the right direction, but it still isn't quite the same level as other places.
Exposure
Yes, BYU has exposure and TV deals from ESPN both for the football team and men's basketball team, however exposure goes so much further than having games on TV. Players like to hear their team talked shown on shows like Sportscenter, to be featured in national articles and talked about by the media. BYU doesn't get that. Sure BYUtv has BYU SportsNation and other sports programming, but they aren't featured on ESPN or Fox Sports unless it is during a game.
Granted, being in a big conference doesn't guarantee that either, when was the last time you saw something about Rutgers? It does however offer up more opportunities. Being in a big conference would give BYU five to six big games a season that would feature teams that are talked about a lot. Right now it is Gonzaga in men's basketball and that is it. And even they are largely ignored until March. Until BYU gets invited fully into a Power Five Conference they won't get much more exposure than they currently get barring something/someone special like Jimmer Fredette.
The Internet
This may be the most surprising but it may also be the biggest difference. Whether it is for recruiting or getting likes on social media, Twitter and Facebook have changed college football and basketball. Coaches no longer have to search long and hard for the most talented recruits, they just have to search on Youtube, MaxPreps or Twitter. It used to be that the best out of state LDS recruits generally went to BYU because it was them or the local state school that was also recruiting them. Unless a player was an elite player that made national headlines they just didn't go anywhere else.
This was a huge advantage to BYU because not only did they get a lot of great Utah recruits, but they had a pool all around the nation. Obviously not everyone was a member of the church, but a very large majority were and a very low percentage ever played at other schools.
Now even the good not great LDS athletes are getting offers from other schools and making it harder for BYU to recruit to them. Without those athletes it makes winning really tough at the D1 level.
Also, before if a player chose to go to BYU or USC it was a small deal as far as who knew about it and how it was celebrated. Maybe the family and school got involved but that was it. Now with social media as big as it is, it goes viral and kids like to see more likes which often comes from the bigger schools.
Other Sports are Helped Out by BYU
Now the question is, if those three things apply to the football and men's basketball teams, why doesn't that affect the other sports? The main reason is that exposure and the internet aren't as big of a factor.
No matter how good a school is at track they probably are going to get the same exposure as any other team, basically nothing until the NCAA Championships. But sports like women's basketball, softball and baseball teams actually get more exposure than normal because of BYUtv Sports.
As far as social media and the internet goes, sure there is still some recruiting that can be done by seeing players play and perform in ways that would not have been possible years ago, but the recruiting and the money has not yet reached the point of football and men's basketball for coaches to travel or bring recruits hundreds of miles for a recruiting meeting.
Sure, things can change, but in today's world where things are quick and money is readily available to big programs it makes it a bit more difficult for BYU to keep up in those two sports.