This is explained and debated a bit in the comments section of the post below.
However, Chicago's 1-0 win over Chivas USA last night not only clinched a second straight Supporters' Shield for Columbus, it also sort of clarifies the Sounders path to various playoff positions ... including potentially No. 1 in the West:
That would happen if the Sounders win against Dallas on Saturday, if Los Angeles loses or draws on Saturday, and if Houston and Chivas draw against each other.
Sounders would finish second -- and thereby get home-pitch advantage of the first round -- with a win over Dallas, an LA win, and a Houston-Chivas draw. OR a Sounders win, LA loss and either Houston or Chivas win.
If Seattle loses Saturday, they finish fourth in the West regardless of any other results.
The point is, LA, Houston and Chivas are all one point ahead of Seattle, and all four teams have one game to go.