Well, the NFL is the standard as far as pro sports leagues go. Why are they so much more popular than MLB or the NBA?
First of all, the NFL promotes the game of football, from pee wee on up. The NBA does not do this. For years, they have promoted dunks and scowls and fancy dribbling. An entire generation has been brought up taught that basketball is something different from what it actually is. A lot of mainstream fans are turned off by the image of scowling dribblers doing nothing but dunking. So they don't watch to begin with. And the ones who tune in expecting that kind of game don't see it, because teams built around one player dribbling the ball for 20 seconds and trying to dunk, then scowling, usually go 13-69.
Other leagues promote their game. The NBA promotes an image that is very different from the product on the floor. It's almost as if they are embarrassed by the actual product. What kind of message do you think that sends? If the NBA isn't proud of their game enough to present it as it really is, then why should America bother watching it?
And this isn't something they can fix overnight. You can't tell America your game is one thing for 20 years, and then wake up and realize you've created this huge disconnect, and all of a sudden say, "huh, we just realized we're really a team game based upon solid fundamentals and skills!"
Now football is especially popular in Texas, the South, and along the East Coast. The NFL does a good job of catering to all kinds of people from different subcultures who are attracted to football to begin with. If you like football, they have something to offer.
Not so the NBA. On the national level, they cater to the hip-hop crowd, the corporate types who buy season tickets, and that's it. Any attempt to branch out is half-hearted and hamfisted. The Midwestern hoops hotbed gets ignored. And they act like the two (inner-city vs. farmbelt) are mutually exclusive. Really? Then why is it that the NFL has inner-city kids AND Texas rednecks AND Pennsylvania blue-collar types loving their league, along with everybody else? If they can do it, why does NBA marketing insist upon giving the middle finger to everybody outside their core base? They act as if the mere idea of appealing to a group of people who love basketball but aren't inner-city blacks is "selling out" or something.
There's another problem in basketball. I can't think of another sport where a player can put up tremendous superstar-caliber statistics while absolutely destroying his own team. The official statistics of the NBA do a poor job of capturing what it takes to win games. The pass that leads to the pass that leads to the assist? Nothing. The screen that gets someone else a wide-open shot? Nothing. The defensive rotation that forces a pass that leads to a contested shot? Nothing.
In the NFL, there are no quarterbacks with a rating over 100 who suck. There aren't any 1500-yard rushers who suck, nor defensive ends with 13 sacks that kill their teams. There aren't any baseball players with a 1.000 OPS that hurt their team's offense. But in basketball, you can have a player that puts up 20 points and 8 assists a night, but who absolutely is destroying his own team's offense and preventing them from winning.
So how did the NBA get in this shape? Well, there never has been a time when the league really penetrated the national consciousness with its team game, per se. It's always been about individual achievement, or the success of major-market teams. When the Celtics won eight les in a row, Wilt was the league's big draw. Then the Knicks with their solid team game were popular, but that was more about being winners in New York than about fans' true love for the game. Once the Knicks and Lakers faded in the '70s, and the league became egalitarian, it almost folded.
The league's renaissance in the '80s was built again upon marketable individuals and success for the big-market teams, in this case the Lakers and Celtics. Then it was the marketing of Michael Jordan and the big-market Bulls that made the league soar. When he took two years off and the team-oriented Rockets were winning, ratings took an immediate nose-dive. Shaq and Kobe -- same thing -- marketable individuals in a major market.
So now the league is in a situation where their most dominant teams are in smaller markets, without highly marketable personalities. This flies in the face of 50 years of experience about what makes the league successful in appealing to a casual audience.
Look again at the NFL. Nobody has parity like the NFL. Teams routinely go from 6-10 one year to deep playoff runs the next. Baseball is moving more in that direction as well. The NBA? Well, they have parity in the sense that small-market teams can succeed, but right now there are probably 20 teams that have zero chance of any serious run next year. Why should fans in Portland or Orlando get excited? Even teams that will make the playoffs like Boston or Philadelphia don't really have a chance to do anything special. So where is the buzz going to come from?
Really the NBA has a ton of problems with their game, with the structure of their league, with their stats, with parity, with marketing, etc. that have a long legacy behind them. All the success they've ever had in their history is based upon marketing the charismatic individuals within the team game, and now that they can't do that, they're forced to sell something that the public never has wanted to buy -- the game itself.
To be bluntly honest, the way things are set up now, the league would be better off if the playing field weren't level, and there were a way to make sure that big-market teams were successful most of the time, like baseball in the 1990's. it would suck for Spurs fans, and it's not a great way to run a sports league, but that's the only model that's ever proven successful for the NBA.