I think it really depended on how each rider had his season mapped-out. The Vuelta is long, hard racing and it's really hot in Spain this time of year. The guys that came over for the CO race were just looking for a little R&R before they start prepping for Worlds(and it showed in the racing).
Cool mountain top finish today (Wed). Winner looked more like a boxer than a cyclsit at the end of the stage.