Well the semantics of "playoff chances" caused it to unravel. The DBacks won't get the wildcard nor will they beat the Dodgers, for instance. Same with the Reds and the Cardinals.
Uh, dummy, the Nats have to contend with the reigning NL Champions. You think NL East teams have some cakewalk yet the Diamondbacks and Reds have it tough because of the Cards and Dodgers?
Let me make it simple:
Dodgers + Rockies = Phillies + Braves (disputable, but it's close enough) > Cardinals + Cubs (or Brewers perhaps)
So you're essentially arguing who's better between the Reds, Giants, and Nats.