Alex Gallardo/Associated Press

Over the past two years, with so many key components to the United States men’s national team choosing to either stay in Major League Soccer or make a return to the league after stints in Europe, the league’s importance to the national team has never been higher.

In addition to Landon Donovan, who has been in the league since he was a teenager, Clint Dempsey and Michael Bradley have returned, while Matt Besler, Omar Gonzalez and Graham Zusi have spurned offers in Europe to stay home.

Ted S. Warren/Associated Press

Additionally, Clarence Goodson, Maurice Edu and Michael Parkhurst returned this past year and a number of other MLS players—notably Kyle Beckerman, Eddie Johnson, Brad Evans and Chris Wondolowski—are expected to compete for playing time on the United States’ World Cup team headed to Brazil this summer.

So with the potential of 13 players (adding in Nick Rimando) on the United States’ World Cup roster coming from MLS, including six players who will most likely start for the red, white and blue, the USA’s performance in Brazil should deliver a clear-cut verdict on the quality, or lack thereof, in MLS.

Or, maybe not.

If the U.S. offense can manage to score against its considerable group-stage foes Ghana, Portugal and Germany, it will likely come from the efforts of Donovan, Dempsey, Bradley and Jozy Altidore. And while all four have played in MLS, only Donovan has spent the majority of his career in MLS.

Dempsey was a promising young striker when he left the New England Revolution for Fulham in 2006, but he truly honed his skills in the English Premier League between 2007 and 2013. Bradley was a youngster for the then-New York MetroStars in 2004 and 2005 but became a top midfielder after stints with Heerenveen, Borussia Monchengladbach, Chievo Verona and, finally, AS Roma.

Mike Stobe/Getty Images

And Altidore, who also played with New York (by then known as the Red Bulls) as a teenager, is still curating his talents in Europe with his most successful stint to date his 2012-13 campaign with AZ Alkmaar in the Netherlands.

So, on the offensive side of things, the USMNT’s best players (save Donovan) have all been developed primarily in Europe.

However, if the U.S. is able to defensively shut down the potent attacks of Ghana, Portugal and Germany, the case for MLS as a legitimate developmental league will be much stronger. In Brazil, the U.S. will likely have two MLS players at center back, Matt Besler and either Omar Gonzalez or Clarence Goodson (although Goodson has only recently returned after six years in Europe).

Geoff Cameron, who came into his own with the Houston Dynamo, will likely start at right back. And DaMarcus Beasley is a favorite to start at left back. Although it has been many years since Beasley has played in MLS, he was already coming into his own before leaving the league for Europe in 2004.

But with the mixed pedigree of many American players, a definitive verdict on MLS based on the United States' World Cup performance will be difficult. However, if one of the few players of a “pure” MLS background proves to be the difference for the U.S. in Brazil, the case for the league will be much stronger.

Christian Petersen/Getty Images

Those players would include the aforementioned Beckerman, Wondolowski, Zusi, Gonzalez, Besler and Donovan—all six of whom have played their entire careers in MLS (Donovan has had three loan stints to Europe and did play seven first-team matches for Bayer Leverkusen in the 2004-05 season). Of those six, four (Donovan, Zusi, Besler and Gonzalez) are projected to start while Beckerman and Wondolowski are thought to be fighting for positions on the roster.

So, in the end, the prospects of using the USMNT’s performance in Brazil as a definitive verdict on MLS are slim. If these six were to be the key difference-makers for the U.S. advancing out of its group—or worse, the key goats for why it didn’t—the potential in using their play to evaluate the league as a whole will be stronger.

If not, we may just have to wait until 2018.

Follow me on Twitter @JohnDHalloran

Follow me on Facebook www.facebook.com/AmericanTouchline