Single miracle sure. Double? Nope. The Nats have played well enough for long enough* that the need for the Nats to play like the best team in baseball and someone in front of them to play suddenly terrible is pretty much gone. Now either should do the trick.
Unfortunately for the Nats what this really means is that no one has collapsed in front of them. Since going 27-10 the Pirates have played under .500 ball and the Braves have been pretty mediocre. Thing is they were clearly the best teams in the National League at the time (16 and 15.5 games ahead of the Nats) so they could afford a little slip-up. The Cardinals and the Reds have both played very well, so while they've lost some ground to the Nats it wasn't enough to pull even with them.
The double header was a nice pick-up but the Reds did what the Reds should do and beat up on the Astros. The Nats have simply held their ground. Which in all honestly is all I was hoping for. At this point the comeback is predicated on two things - Nats sweeping the Marlins and playing .500 ball vs the rest, the Pirates taking care of the Reds winning at least 5 of the 6 and the Reds playing .500 ball vs the rest.
Under that combination - Nats go 8-3, Reds go 3-7 there would be a tiebreaker final game of the season.
You see though that that IS pretty much a Reds collapse. If you give the Reds some leeway not to collapse, 4-6 or 5-5, then the Nats have to be close to perfect 9-2 or 10-1. Either way another 11 "miracle" is needed. But at least it's only 1.
(The Pirates, Cardinals and Braves all still require some version of the double miracle)
What's the most likely scenario? I'll say this
Nats win 3 of 4 vs Marlins, win 4 of the 7 other games to finish with 88 wins.
Reds beat Astros tonight, take 2 of 3 from the Mets, split with the Pirates to finish with 92 wins
Pirates take 3 of 5 vs Pads and Cubs, split with Reds, win 93 games
Of course if we were dealing with most likely scenarios we wouldn't be where we are now.
Beat the Braves, Sweep the Marlins. See where you are.
*Depending on how far back you want to go 10-1, 21-6, or 27-10.