Major League Soccer made one of the biggest announcements in its 18-year history on Wednesday, unveiling a partnership with the United Soccer Leagues to run its Reserve League within the USL PRO league structure.

Starting this year, there will be interleague play between USL PRO and MLS Reserve League teams. This will include the creation of several formal affiliations between USL and MLS clubs.

Although no official affiliations were detailed in the USL's release, I can confirm that the Philadelphia Union will be paired up with the Harrisburg City Islanders. This continues a relationship which has existed less formally since the Union's inception, as players have moved back and forth between the clubs via loans. Now the City Islanders will actually be the Union's reserve team.

Further affiliations will be announced in coming days and months, but information is already starting to tricke out.

Within minutes of the initial announcement, Sporting Kansas City revealed that it has paired up with Orlando City, one of the best-supported USL PRO clubs. In addition, the NBC affiliate in Rochester, N.Y., reported that there is a "verbal agreement" between the New England Revolution and the Rochester Rhinos.

Another partnership that's likely to happen - though it hasn't been formally announced yet - is between D.C. United and the Richmond Kickers. Those two clubs have worked together for years, in a way similar to the deal between the Union and City Islanders.

Brian Straus of The Sporting News reported that those four partnerships will be the only ones this year.

It's worth noting that MLS clubs will not be required to be affiliated with USL Pro clubs. And it wouldn't be possible for every MLS team to get a USL PRO affiliate anyway. There are 19 teams in MLS, but only 13 teams in USL PRO - and one of them, the Antigua Barracuda, won't get a MLS partner because of travel costs.

Here are more details on how the deal will work, from the official press release:

Each club affiliation will be customized to meet the needs of the respective teams, but all will include at least four players on long-term loan from the MLS parent club to its USL PRO affiliate. Those MLS teams with formal USL PRO affiliates will not participate in the 2013 MLS Reserve League.


Each of the 13 USL PRO teams will compete in two interleague games against MLS Reserve teams. With the exception of Antigua, which will play both of its games at MLS Reserve teams, USL PRO teams have been paired with a single MLS team to play a home and home series.

All interleague games will count in both the official USL PRO and MLS Reserve League standings. Details of the fixtures will be announced in conjunction with the forthcoming release of the official 2013 USL PRO schedule.

As for how players will move between MLS and USL clubs, it appears that MLS clubs will have wide latitude in their ability to call up players from the lower division. The Rochester Democrat and Chronicle's Jeff DiVeronica reports that MLS clubs will be able to call up any player on the affiliated USL team, regardless of which team owns that player's contract.

So the system will resemble those used by Major League Baseball and the National Hockey League.

I know that many of you take a deep interest in the player development side of American soccer, and I do as well. This news is a major step in improving how that process works in the United States. By partnering with the USL, MLS has found a more pragmatic way to execute what has always been a good idea in theory.

I'm sure that some of you are also wondering why this is such a big deal. Here's the simplest way I can explain it.

Think of all the draft picks and homegrown signings who never see the field at PPL Park. Guys like backup Union defender Ray Gaddis and homegrown midfielder Jimmy McLaughlin, both of whom have immense potential.

A reserve league gives those players a place to play games on a regular basis. A strong reserve league gives those games meaning, instead of them being just glorified scrimmages.

MLS and its clubs are certainly aware of this, which is why the league has tried twice to run a reserve league in its history.

The first reserve league existed from the 2005 through 2008 seasons. It featured a 12-game schedule and a single, league-wide table. Whichever team finished in first place received a $20,000 bonus.

But because of travel costs and scheduling difficulties, the reserve league proved unsustainable. So it disappeared for two years.

The reserve league returned in 2011 with a three-division format based on geography, and the team with the most points overall was crowned the champion. There was no financial bonus, but the divisional format allowed for reduced travel costs.

Reserve league games were often paired with first-team games, so that squads would travel together to road games. Sometimes there were doubleheaders, though they generally were not publicized.

All too often, though, reserve league games were played on practice fields or at recreational facilities, instead of proper soccer venues. Games were also often postponed or canceled due to various logistical issues.

Under the new arrangement, scheduling reserve league games as doubleheaders at MLS venues will be much more formalized. Hopefully they will be much more accessible as well.

When games take place at existing USL PRO venues instead of MLS venues - such as Harrisburg's Skyline Sports Complex - that will likely help increase exposure to MLS outside of places where it is already well-known.

To pick just few examples, there were USL Pro teams in Pittsburgh, Charlotte, Orlando and Charleston. Next year, there will be an expansion team in Phoenix. None of those cities have MLS clubs.

In particular, having affiliate teams in southern cities will get MLS much-needed exposure in that region. The league has lacked a footprint in the Southeast since Tampa and Miami were contracted in 2001.

This deal may not truly be the top division - and Orlando is well-known to want to join MLS - but it will help MLS judge just how much interest there is in soccer in those markets.