While the Seattle Sounders will not be participating in the most dramatic aspects of the MLS-USL Pro partnership, their currently limited involvement is coming into more focus. For the 2013 season, that means the Sounders Reserves will play Orlando City SC in a home-and-home (at Starfire May 12th 5PM, at Orlando Aug 11 7:30PM). Those games will count in the standings of both the MLS Reserve League and the USL Pro.
Beyond that, the Sounders' role in the partnership is still very much a work in progress. Black and Red United had a good writeup of some of the finer details here, but few of those will immediately affect the Sounders outside of the home-and-home.
It does, however, outline future implications on the Sounders' youth development. There are now three options for MLS teams to work with USL Pro affiliates: 1. teams can continue to field reserve sides, which will ultimately play more games against USL Pro opponents; 2. they can affiliate with an existing team, sending at least four players to the lower division on long-term loans; 3. they can actually operate their own affiliate.
Considering the closest existing USL Pro team to Seattle is the LA Blues, it probably shouldn't come as much of a surprise that the Sounders are not currently affiliated with a lower-division team.
And while it seems unlikely that the Sounders would be interested in directly operating a USL Pro team, I could envision some kind of hybrid where they help recruit an ownership group that they would work with as a way of expanding the Sounders brand to other parts of the state. That could mean creating a relationship similar to the one they have with the Sounders U23s and getting a team in Tacoma or finding a new group to run a team somewhere like Everett, Bremerton, Bellingham or Tri-Cities.
Assuming the Portland Timbers and Vancouver Whitecaps undertake similar efforts, it's entirely plausible that another level of regional rivalry could develop. In 2014, there will already be existing USL Pro teams in Phoenix, Sacramento and Los Angeles, lower-division teams in the Pacific Northwest suddenly look viable again.
Having this kind of affiliate would have some definite benefits over the current Reserve League, most of them tied to simple fact that USL Pro teams play more than twice as many games.
The biggest and most obvious would be that the Sounders would finally have a viable way to get their young players meaningful minutes on a regular basis. As much as an improvement the current set-up is, the reality is that with only 10 games spread out over seven months, there were several instances where the Reserves went more than a month without a competitive match. That's obviously less than an ideal way for developing someone like Cordell Cato, for instance, and helps explain why the Sounders may be reluctant to expend too many resources on a player they don't think is entirely ready to contribute at the MLS level. It would also make it far more likely for the Sounders to sign more Homegrown Players, as they wouldn't be forced to sit idly for long stretches of time.
This kind of set-up would also potentially provide even more opportunities for Academy players. As it is now, academy players are often invited to participate in reserve games, but mostly only as late substitutes. Academy players would still be allowed to play in the USL Pro, and probably have twice as many chances to get into games.
It would also have the ability to give rehabbing players more chances to test themselves. Someone like Steve Zakuani had to wait weeks between competitive appearances while he was coming back from injury a year ago. If the Sounders had a USL Pro affiliate, he could have been sent down on a loan and probably seen his comeback sped up considerably.