As Major League Soccer begins its 13th season, there's a few interesting stories developing. MLS Cup champions Houston and runners-up New England return much of the same team that returned them to the final match last year. Western Conference champions Chivas USA also return many of the same players, but may lose star keeper Brad Guzan to the EPL in the July transfer window. Supporters' Shield winners DC United return a totally retooled team, and it will be interesting to see if the new players can 
