11 teams have come from 0-2 down to win the World Series. Five have come from 1-3 down. So it happens, on average, once or twice a decade. Even if the Nats do lose later today, if they do so in the meek manner they've lost the last two games I would argue that they were simply beaten by a superior team, one that probably should have won Game 1 and nearly did against a Nats bullpen that was one of the worst in their league in the regular season. Game 2 is the outlier here.
"Choke" would be a harsh word to use on a team that only measured up to its opponent in the quality of its top two starting pitchers, and even then, one would have had to give a slight edge to Cole and Verlander over Strasburg and Scherzer coming in. And now Scherzer is injured and the No. 3 starter, Corbin, has been used as a relief pitcher because the manager -- justifiably -- doesn't trust most of his relievers. If the Astros lose these next two games at home, especially if they blow late leads in both, that would be a huge surprise and, I'd argue, a far more historic choke than Washington losing from 2-0 up.
Come to think of it, this World Series has already been historic in that the home team has lost all five games so far. That has never happened even once in Series history. It also has contributed to the generally flat feel of the Series so far. Winners celebrating in front of a nearly silent crowd, a good portion of which has already left the ballpark, is not a good visual.