Major League Soccer is a growing league. Los Angeles Football Club joins as the 23rd team this season, with Nashville, Miami and at least three more clubs on the horizon.

Last year, Atlanta United and Minnesota United came online with different visions of how to succeed in America's top flight. The divergent paths each team went down offer ideas for the future, providing possible models for the clubs that come next. Should Atlanta's outsize ambition be a guide? Or does Minnesota's slower start make more sense? The truth is out there. Welcome to the good, the bad and the ugly of MLS expansion.

The Good

With a few minor exceptions, expansion has been an unqualified success for MLS. In 2017, the five squads with the highest average attendance -- Atlanta, Seattle Sounders, Toronto FC, Orlando City and New York City FC -- did not exist a decade earlier. Atlanta's debut season smashed records with 48,200 fans a game, a figure that put the team near the top 20 in the world. While Minnesota didn't have the same level of success, the club still averaged more than 20,500 fans per game, good enough for 10th in the league.

In their first year, both Atlanta and Minnesota did an excellent job of capitalizing on the passion of their local fan base. While Atlanta created something out of nothing, Minnesota had a built-in advantage.

"We have a 40-year history of soccer in Minnesota with the Minnesota Kicks, the Strikers and the Thunder," said Chris Wright, who joined MNUFC as CEO this past September. "It's an embedded, deep-rooted, core fan base that has seen many different iterations, but our fan base is knowledgeable about the game. That's an incredible platform to work from."

If future teams are going to succeed, they need to start at the grassroots level. That sounds obvious, but some clubs in MLS forget that group, and attendance has suffered for it.

Wright also said that the league offices help expansion franchises determine their business models. MNUFC came into the league playing in a third-party stadium, just like Atlanta and Orlando. Nashville and David Beckham's Miami team likely will, as well.

"The league has all of the data on all of the teams that have come in and the recent history of those that have come in, as well," Wright said. Being able to take a look at the numbers helped MNUFC determine their ticket strategy, the type of revenue they could expect to generate and went a long way toward determining how to build a business. MLS' single-entity structure is a major advantage in this regard.

The Bad

Atlanta entered MLS with massive ambition and the payroll to match. It built a soccer culture in the city where hardly any had existed previously, and the entire project took on a momentum of its own. It established a new level of success, and teams around the league took note.

Minnesota United and Atlanta United joined MLS in 2017 with very different blueprints for success. Brett Davis-USA TODAY Sports

"The thing that I respect most of anything is that they built a plan for everything they wanted to accomplish down there and they stuck to the plan," Wright said. "They executed on a plan that was absolutely magnificent. Is that great for our game? It's unbelievably powerful for our game. It sets a tone for our game. It sets a bar for every other franchise here in the league. It sets a bar for professional soccer. But it's a different bar. It's their version of this great game. You have to respect the way that they did it."

Respect, yes. But there's a chance new teams might fail to live up to the outsize expectations Atlanta created.

In past years, Minnesota United's inaugural season -- one in which the club finished a respectable ninth in the Western Conference with a payroll of less than $5 million and drew large crowds -- would have been considered an unmitigated accomplishment. In light of Atlanta United, however, it was something of a failure, at least to some outside observers. Future expansion franchises run the risk of being compared to Atlanta's success, as well, a standard that will be difficult for some entrants to achieve.

The Ugly

Going forward, every expansion franchise will follow its own ideas and look to achieve its own goals. The idea is to build a brand in your area. Some teams will have large ambitions. LAFC, for example, seems to be more in the Atlanta United mold with high-priced signings such as Carlos Vela and a potential teenage superstar in Uruguay's Diego Rossi. Wright thinks Miami will be, as well.

"What's Beckham going to build down in Miami? Look at the power of the David Beckham group that has just come into our league," he said. "Single-handedly, that's going to take the bar and push it even higher. And all of that is OK. From an aspirational standpoint, we're all trying to achieve that level of greatness inside our own markets."

Other squads, such as Nashville -- and hopefuls such as Sacramento, Cincinnati and Detroit -- will likely have lower ambitions at first. That's fine, too. The worst thing to do when it comes to expansion is to try to do too much too soon.

At some point, the teams need to succeed on the field, too.

When the Philadelphia Union joined MLS in 2010, they were one of the best examples of a successful expansion franchise. They boasted a passionate fan base that launched the Sons of Ben supporters group before a team existed. But on-field struggles are destroying enthusiasm. Last season, they drew just 16,812 fans, down 4 percent from 2016 and almost 2,500 fewer supporters than during their debut. While that figure still represents 91 percent capacity at Talen Energy Stadium, it's a concerning downward trend for a club that has finished higher than sixth in the Eastern Conference just once in eight years.

Even if an expansion team starts strong with its base supporters, results need to be good on the field or else things can get ugly, fast.