Trailists are a lot of fun. They exude promise and hope. Once in a while they explode and are season changing. Most of the time they disappear as soon as you get to know them. The roster bubble is not the only bubble. Those last three spots are mainly used for development, not to win right now.
There are two other bubbles in squad construction - the Ideal XI and the Gameday 18. After the trip to Charleston and the Carolina Challenge Cup all three bubbles will pop.
This is pretty much set except in two places when everyone is healthy and present. There is a question at keeper. While Stefan Frei earned the Arizona starts Sigi Schmid and Tom Dutra are still saying that Marcus Hahnemann is competing for the number one spot.
There is also at the non-Marshall centerback. Djimi Traore has more starts there with Marshall, but Anibaba's been used at right back to fill in for Yedlin quite a bit.
Left back is not yet a question. Sigi's essentially said that Leo Gonzalez will be back starting. But Remick is showing great things up to the half way point of the preseason.
The other keeper. That's easy. After that it doesn't get easy.
Two defenders - three that seem likely to deserve time. Jalil Anibaba or Traore make sense. Remick's been great and there's Zach Scott. He looks as strong as ever and his ability to work all for spots on the backline make him a valuable injury replacement.
Central Midfield - there are three that fit well here. One is a trialist and if Gonzalo Pineda makes the roster he's likely to fit here. He's the type of signing that only makes sense for regular 18 time. Andy Rose is having a great preseason slotting in with the first team. Let's call him a lock. Alex Caskey can slot in the middle or wide. Let's push him down to the next discussion.
Attacking mids/forwards - There is one likely guarantee in Lamar Neagle. Caskey could be chosen with his possession based game. Chad Barrett provides forward defense and has been a decent MLS scorer in the past. Tristan Bowen is emerging into his youth peak and fits wide or up top. David Estrada knows full field pressure and can pop in a goal or two.
It's a numbers game really. If Pineda makes the roster than only one of Barrett, Bowen, Caskey and Estrada are likely to be in the 18 regularly. Even if he doesn't then there's only two of those four on the bench for Sigi to change tactics or give Oba, Cooper, Dempsey, Evans and Pappa rest. The bubble for those six outfield players is the one most likely to change on a game-to-game basis.
This is the land of trialists and non-contract draftees. There are four spots open at this time. Currently to these untrained eyes Parsemain and Azira are clear leaders. Scoring goals and playing a lot are generally positive signs. Pineda also feels likely after the praise he recent grabbed. But there are others.
Many, but not all, will get their chance down in South Carolina. Seattle Sounders FC added a match against the College of Charleston, and likely another scrimmage/non-tourney game later, specifically to get players time. One could pop. They could claim the bubble as their own.
Maybe Adrian & Co work out a loan of some of their young talent outside of the 18 bubble to get them development time. Perhaps that deal involves a player on a full season loan with the contract picked up by the acquiring side. Then Seattle gets an extra trialist on the squad.
There will be four or five matches in Charleston that determine the intended XI, 18 and roster for 2014.