The winning goal came when Evans headed in a corner kick from Mario Roberto Martinez in the 77th minute for Seattle.
Seattle finished with nine points in Group Four.
Ochoa gave Seattle a 1-0 lead with a goal in the 11th minute.
Mario Berrios of Marathon tied it with a penalty kick in the 34th minute.
Eddie Johnson gave Seattle a lead in the 62th minute. The Marathon's Berrios tied it again with a second penalty kick five minutes later.
Both teams played two years ago with the Marathon getting a 2-1 win against the Sounders. And they will play again in Seattle on Oct. 24.