The Dodgers hadn't played a meaningful baseball game in months while the Nationals were basically in a fight through the last weekend? I'd imagine it's pretty hard to turn it on when you haven't been pushed really all season.
Sucks when teams that run away with their division lose to teams with inferior records, but both the Cardinals and the Nationals had to turn it on after the all star break to make the playoffs they've just carried it through.
Of course the flip side to that is the Yankees who have just continued beating the crap out of everyone...