It's a legit question. On May 28th the Nats lost to Miami and dropped to 25-27. Since then they've gone 29-16 or the pace of a 104 win team. Normally I hate the "since May 9th" type of things, but in this case it's clear that the Nats have become a better team over time.
Pre-season : Fister out
March 31st : Ramos out
April 12th : Zimmerman out
April 25th : Bryce out
Three weeks into the season they lost a Top 3 starter and starters at 3 positions. That's tough to overcome.
May 7th : Ramos back
May 9th : Fister back
May 9th : LaRoche out
Early May looked like it might be the turning point but as soon as they got a couple guys back they lost another bat. It felt like they might never be healthy and it showed in their play.
May 25th : LaRoche back
June 3rd : Zimmerman back
June 10th : Ramos out again
June 26th : Ramos back
June 30th : Bryce back
But from the end of May until the end of June the team has finally come together mostly on a straight path with the exception of Ramos being out again for a couple weeks.
The gist is, I'm not saying the Nats are a 100+ win team, but the month+ long run they've been on is no mirage and the 2 month stretch prior to that is almost irrelevant. That team, from Mid April to the end of May was a different team and only serves to show how things could fall if there is another run of injuries. If not, like we've said before, like everyone said before except the Braviest of Braves fans, the Nats should take the East.
Are they the best team in the NL? I think so. The run differential (which they lead) highlights the Nats' lack of flaws. They are a half-run better than league average when it comes to runs allowed per game, 2nd only to San Diego who plays in a run-depressing park. They are 3rd in the NL in runs per game and while that's not close to being as impressive as the pitching* it still means you are talking about a squad that's better than average now and likely has room to improve as guys get healthy and round into form.
In baseball? That's tougher. Both Detroit and Oakland have teams that are doing well both offensively and defensively. I'm not quite ready to say this. Let's see where the Nats are in a month though.
Looking at this, screw 5-4, road or not. I'm going for that 7-2 run. Let's start putting the East away.
*they are less than a quarter run better than average. Or let's put it another way - the difference between the Nats offense and the 2nd to worst offense in the NL is 0.48 runs. That's equal to the gap between the Nats pitching and the average. The same kind of stretch comparison - we'll compare to the 3rd worst since the D-backs are a step worse than everyone else and the Rockies are the Rockies - get the Nats pitching to a 0.92 run difference.