Promotion and relegation is a common practice in leagues around the world, but not in MLS. More and more people are asking why.

Landon Donovan has a lot of free time on his hands these days.

The retired American soccer legend has made a seamless transition from the playing field to the post-player life. He has dabbled in television work, and even some coaching, while he enjoys the comfort of retirement and awaits the birth of his first child.

Among Donovan's new hobbies is social media, and the former LA Galaxy star hasn't been afraid to engage followers in topics he considers interesting ones. Earlier this week on Twitter, he asked a group of American soccer journalists what they thought of the topic of promotion and relegation, and as is often the case with that volatile topic, a simple question stirred up a bit of a firestorm.

The thing about Donovan's public inquiry about a topic that had long been a virtual taboo talking point is that he is far from alone in discussing the topic. These days, promotion/relegation is popping up in American soccer discussions far more frequently than ever, and unlike years past, when most would do their best to avoid discussing it, we are getting more and more public discourse.

To the uninitiated, promotion/relegation is the system by which professional leagues can be set up in tiers, with a league's worst teams being dropped down a division in a given year while the best teams in the division below can move up to a higher league. It is the standard system of professional soccer around the world, with the United States being the glaring exception.

"There are many complicated factors that need to be considered when discussing promotion/relegation in this country. I understand both sides of the argument," Donovan told Goal. "One thing we shouldn't do is simply write it off and not seriously discuss it. Soccer in this country is bigger than just a handful of markets that have MLS teams. In the end, soccer needs to win and perhaps we can find creative ways to give deserving markets a chance to be part of Major League Soccer."

Promotion/relegation has never been a part of top-level professional American soccer, not in any of the previous professional incarnations of the sport, and not in the current setup. As the number of American soccer fans who follow international club soccer continues to grow, the questions about and calls for, promotion/relegation grow. That has forced MLS officials to start publicly addressing the topic, even though their general view of promotion/relegation has not changed.

As far as MLS is concerned, promotion and relegation isn't a system that makes sense to try and establish in the current professional sports setup.

"Promotion and relegation was created in the 1800s," Garber said at a recent soccer event in New York. "It was a system that existed because there was no other way that existed to create good competition. They were amateur teams. If you were to create professional football in England or Italy or Spain today, I don't believe you'd have promotion and relegation. We need to create a league that works for the fan base in this market.

"Nobody looks at the NFL and says it's not working because there's no promotion and relegation."

MLS's aversion to promotion/relegation isn't exactly a surprise given the financial risk involved in having teams paying nine-figure expansion fees and investing considerable amounts of money to be in MLS only to risk that investment on being dropped to a lower division after one bad season.

"If you're investing billions and billions of dollars, which we are now at about $3.5 billion invested (in MLS) in 20 years, to build something in Kansas City and they have a (crappy) season, to think they might be playing in Chattanooga in a stadium of 4,000 people on a crappy field with no fans, makes no sense," Garber said.

If promotion and relegation were to happen in the United States, it would not be MLS' decision to make. U.S. Soccer ultimately has the authority to force the country's professional leagues to establish a system of promotion and relegation, but U.S. Soccer president Sunil Gulati has made it clear the federation isn't about to simply impose that system on the current pro leagues, not least of all because it could lead to a serious legal battle with clubs who would see their considerable investments threatened by a change in league structures.

"It's safe to say that if the federation imposed all the powers that it might have via the Ted Stevens Act, and its membership in FIFA, there would be very long discussions with many people with high LSAT scores," Gulati told reporters prior to the U.S. national team's recent World Cup qualifying win against St. Vincent and the Grenadines.

Gulati stopped short of saying promotion and relegation could never happen, but made it clear it won't happen until the country's established leagues push for it to happen.

"Does that mean that promotion/relegation could never happen? No, I'm not saying that," Gulati clarified. "But to think that we would, from a federation standpoint, say it's happening, 'figure it out or this is what you're doing', I think that's a rather different setup than when it's happened organically and people knew the rules."

Another reason for the increased interest in promotion and relegation is the increasing number of professional teams popping up around the country. MLS continues to grow and will reach 24 teams in the next few years, with a 28-team league not too far away. The North American Soccer League, the current American second division, is also seeing rapid growth, with NASL commissioner Bill Peterson saying the league could reach 16 teams very soon.

The list of those who support promotion and relegation in American soccer continues to grow, with current U.S. national team coach Jurgen Klinsmann and former U.S. coach Bob Bradley among the many who see the benefits of it, and need for it.

"I am a huge fan of promotion/relegation but I'm not sure it's going to happen. I'm not sure everyone in the U.S. is ready for it," Bradley told The Associated Press. "When you see what goes on at the end of seasons in Europe. I've see it for years but I have experienced it the last two years. When you see what happens when teams go up, when you see the battle to stay up, this part is tremendous.

"To get to that point you have to continue to grow," he added. "I don't think there's anything wrong in saying that there have been some owners in the league over the course of the history that have definitely made big contributions to the growth of soccer in the United States. The owner when I was in Chicago was Phil Anschutz who is now the owner at the Galaxy. so when you are around a guy like Mr. Anschutz and you see what he has put into the game then when you want to have a real discussion going forward about how to put promotion and relegation in place it still has to be done with respect to him.

"Can that happen? I hope so. I think that would be great for the game. I don’t think I’d be here in Europe if I wasn’t a purist in many ways. I still love promotion/relegation."

Klinsmann made waves a year ago when he touched on the subject of promotion and relegation, making it clear he wished U.S. Soccer would adopt the structure.

"I just wish that we would have a system in place where all the young players and all the players in general know that there's the next higher level and there's a lower level (and think), 'If I play a bad season, then that lower level is waiting for me,'" Klinsmann said in October of 2014. "If I play a very, very good season then there's the chance to go up and play at whatever you describe then as the highest level."

U.S. national team star Clint Dempsey has experienced both systems, having played in England in the promotion/relegation system, and having played in MLS. He sees benefits for both structures, but isn't sure promotion and relegation would work in the U.S.

“If you ask me at different times I think differently about it. I like the idea of promotion and relegation in terms of any team can make something of themselves and move up and play at the highest level possible, like a Cinderella story," Dempsey told Goal USA in 2014. “What I don’t like about it is the way it changes how things are, and even though it’s business, it makes it even more cutthroat. When you’re playing, it’s always stress because if the team gets relegated then you’re not going to be playing in the best league, you’re going to be playing down a league. It’s going to affect people’s wages. It could affect that club in terms of what the future holds because they’ll have to sell some players and try to keep some players because you’re missing out on the money from TV deals."

The financial realities of professional sports in America make promotion/relegation something we aren't likely to see any time soon, and we won't see it until the country's lower divisions grow stronger and close the gap between themselves and MLS. Proponents of promotion and relegation will argue that the gaps can't close without promotion and relegation, but other pro sports in this country have seen upstart leagues put pressure on the established top leagues. American football saw the AFL push the NFL into a merger in 1966, and the ABA forced the NBA into a merger in 1976. In both instances, the newer leagues grew into viable direct competitors and reached a point where the established leagues had no choice but to negotiate and create new leagues.

If MLS keeps growing, and NASL keeps growing, and USL keeps growing, we could see promotion and relegation eventually, but that still feels like a long time from now. . That said, the fact that the discussion has gone from "it will never happen" to "it won't happen soon" feels like progress, as does the fact a once-taboo topic is becoming a more regular subject for discussion in American soccer circles.