For the first time in the history of the USL, two teams owned by MLS clubs will play in the USL Cup final. While the feat is impressive, USL President Jake Edwards says the partnership remains a work in progress.

The sales staff has been reaching out to season ticket holders. The digital team has been boosting coverage on the club website. And there’s the hope that a few committed supporters attending Sunday afternoon’s MLS game in Philadelphia will rush up I-95 in time to reach Harrison, NJ and Red Bull Arena by the 8 PM kickoff. Combined, that should be enough to help New York Red Bulls II, the reserve outfit playing in the United Soccer League, set an attendance record at Sunday night’s title game.

The Red Bulls, their opponent (Sporting Kansas City’s Swope Park Rangers) and the USL will hope that’s enough to provide a worthy championship atmosphere and a suitable backdrop for ESPNU’s cameras. But there’s no guarantee. That’s because NYRBII’s record high attendance is a mere 2,096. Double that total, and the crowd still will be overwhelmed by 20,000 empty seats. Despite posting the best regular season record in the 29-team USL, NYRBII is used to playing in relative peace and quiet. This season, its second, it attracted just 589 fans per game.

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The USL, which occupies the nominal third tier of the American pro soccer pyramid, is growing fast. Boosted by a 2013 agreement that permits MLS clubs to either field their own reserve squads in USL or affiliate with independent USL organizations, the USL has nearly doubled from 14 teams in 2014 to 29 this year. And it will surpass 30 in 2016 thanks in part to the expected addition of the Tampa Bay Rowdies and Ottawa Fury, whose decision to leave the second-tier North American Soccer League represents a massive vote of confidence in the lower but larger circuit.

The USL’s average attendance surpassed 3,400 this year, led by jaw-dropping crowds at FC Cincinnati (17,296 per game) and Sacramento Republic (11,514) matches. But the league-wide figure was suppressed by the MLS reserve teams, which typically share a name/brand, stadium/market or both with the parent club. Thirteen USL teams drew fewer than 2,000 fans per game in 2016, and eight of those have MLS owners. And those owners probably aren’t too worked up about those statistics. Their USL teams exist in order to provide priceless professional minutes to young or developing players who might otherwise be languishing on an MLS bench. New York Red Bulls technical director Ali Curtis and head coach Jesse Marsch surely are pleased with the progress made by NYRBII, where players like all-USL forward Brandon Allen, goalkeeper Ryan Meara and homegrown teenagers Derrick Etienne and Tyler Adams have flourished. But the USL’s independent clubs and league front office measure success with additional metrics, and as the circuit grows and vies to secure second division status form the U.S. Soccer Federation, tiny crowds in some of its biggest markets are a growing concern.

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The MLS-USL partnership certainly has benefited both parties. But it remains, as USL president Jake Edwards says, a work in progress.

“The addition of the MLS second teams has helped raise the level of competition. I think our competition gets harder and harder every season, and that’s despite having more players and more teams. The level of quality coming into the league goes up each year,” Edwards told SI.com. “We’ve taken some really positive steps forward and are learning what has worked and maybe what wasn’t working, and we’re at the stage now, after three seasons of doing this, where some of the things we weren’t concerned with or didn’t think of have appeared as potential opportunities to explore further.”

Most MLS club front offices focus on selling and marketing the MLS team. There’s not much bandwidth left over to pitch minor league soccer, and with the technical staff preferring to stay close to their players, it originally made sense to field USL teams nearby. It was preferable for financial reasons as well—no USL expansion fee was required if the new team was based in the MLS club’s designated operating territory. Doubling down on the brand, as European clubs do with their reserve teams, made sense as well. The LA Galaxy launched LA Galaxy II in 2014 and most games were played down the street from the MLS arena at StubHub Center’s 2,000-seat track and field stadium. In 2015, NYRBII came aboard along with FC Montreal, Portland Timbers 2, Real Monarchs, Seattle Sounders 2, Toronto FC II and Vancouver Whitecaps 2. That year, six of the eight teams at the foot of the USL attendance chart, including the bottom four, were owned by MLS clubs.

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Edwards and the USL did, and this year it started to change.

“It’s a conversation more and more now with the business offices of those clubs and not always completely driven by the technical staff, where it started. It’s not a much more robust conversation with the ownership levels of those clubs,” he said. “These players need to play in a professional environment. You can’t go on the road and play in front of 20,000 at Cincinnati and then come home and play in front of a few hundred. If that’s how the clubs want to approach it, that’s not the model for us. That scenario can’t continue because ultimately, it’s a disservice to those players and to the independent teams that are putting millions of dollars into their stadiums and their programs.”

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MLS clubs took a few more chances in 2016. Sporting Kansas City named its USL team Swope Park Rangers, after the location of its stadium on the Missouri side of the river. Orlando City calls their team Orlando City B, but plays games in Melbourne, Florida, about an hour southeast of the Citrus Bowl (it didn’t work—OCB averaged 958 fans per game, but at least they tried.) And the Philadelphia Union and Houston Dynamo took an approach that might define the future of the MLS-USL partnership. The Union put its USL team in Pennsylvania’s Lehigh Valley and named it Bethlehem Steel, after the famous five-time U.S. Open Cup champion of the 1910s and ‘20s. The 2,573 fans welcomed to games at Lehigh University’s Goodman Stadium this season represented the best average crowd among the MLS-owned USL teams (the overall league average was 3,439). The Dynamo took it a step further, entering into an agreement with the expansion Rio Grande Valley Toros, under which the MLS club will control the soccer operation on behalf of an independent ownership group. Next year, the San Jose Earthquakes will enter a similar arrangement with Reno 1868 in western Nevada.

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“We’ve been very cautious looking at that model but it’s been very successful for Houston and RGV and we don’t have any reason to believe it won’t be successful for San Jose. We’ve been working to make sure the model protects both clubs and that it continues to push the competition higher—you’ve got an independent ownership group focused on the business, stadium and building the club in that community,” Edwards said.

“I think more and more MLS teams are looking at that,” he continued. “Portland are looking at an independent group we’ve put together in Boise. Seattle is looking to partner with a group in Tacoma. I think this will be a model we see more of. It certainly makes sense toward achieving everyone’s goals. Some [MLS] teams will still be committed to that ‘second team’ structure, and maybe that will work for them. Where we are now with this partnership and this affiliate model isn’t where we’re going to be in a couple years … It won’t be a dramatic shift for next season but I think you’ll see some changes for 2018. Whether they’re MLS-owned or independent teams, if they’re not able to meet the standards and operate a team and create an environment at the level we require, they won’t continue.”

Some MLS teams will choose not to make an investment in a full USL side and will continue to affiliate with independent teams. That typically involves loaning a handful of players. Relationships like the one between D.C. United and the Richmond Kickers, or the New England Revolution and Rochester Rhinos, have several years of traction and seem to work for those involved. Meanwhile, the second-team model already is starting to pay off at the MLS level. Defender Daniel Steres spent 2014-15 with Galaxy II and this year has started 29 games for the big club. Goalkeeper Jake Gleeson spent two seasons in USL and now starts for Portland. And 15-year-old Alphonso Davies was given his pro debut with Whitecaps 2 before becoming the third-youngest player in MLS history when he signed an MLS deal in July. There are others.

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But moving forward, the USL wants to strike a balance between development and environment, between its role as a reserve league for MLS and the only league for mid-size markets throughout the U.S. and Canada. That’s the way its done in Germany and Spain, for example—there are rules prohibiting the promotion of second teams to the same division as the first team—and Edwards is confident the formula exists that eventually will make the USL “one of the top second divisions in the world.”

He said he has no issue with NYRBII and Swope Park, two MLS-owned teams, facing off in Sunday’s final.

“They absolutely deserve to be there. They’ve had tremendous seasons,” he said. “We’re happy with the competitive balance,” between MLS-owned and independent teams.

But eventually, the USL expects to not have to scramble to fill a stadium for the final. And if the Red Bulls host again in 2017, it won’t have to. NYRBII is moving next year from the big MLS stadium to Montclair State University’s Pittser Soccer Complex. The club will pay to increase capacity, improve the press facilities and lay the groundwork for video streaming. Tickets will be cheaper and a new fan base might be cultivated deeper into New Jersey. It's a step. Every market is unique. Every club has different resources and priorities. But as the MLS-USL partnership evolves, Edwards wants to ensure that both sides remain vigilant and committed to exploring new ideas.

“We want to be good partners and MLS has been tremendous partners,” Edwards said. “You can’t solve everyone’s problems. We’re continuing to look for solutions that make the most sense for everybody … It’s about providing more options perhaps then what has been provided so far.”