Every loss matters and losses versus division rivals doubly so because you are guaranteeing them a win. But there are others thing to consider that determine how much you should concern yourself with them, like where the teams are, where they are headed, and how much time is left.
The Nats are in first and getting healthy with Bryce Harper coming back soon. The Braves are trailing and just lost another pitcher in this "God doesn't want you to win" year for them. With 90 to go, the Nats could lose all four games and still be in good position. No one wants it to happen. It's obviously better if it doesn't happen, but it's not going to kill this team to lose these games.
If this division was different, if the Braves were healthy or the Marlins ready, then you can go overboard with these losses because they are probably putting the Nats 5, 7 9 games back. Instead the Nats might lose the series and fall... a half game out of first. The reality of the season in front of us lessens the impact of these losses where they really matter - in the standings.
Where they remain large is in the nebulous realm of reporting about the team. The losses to the Braves are a story. The Braves are in Nats fans heads, possibly in the Nats heads. Nevermind two years ago the Nats did beat the Braves more than they lost and won the division, so it isn't an epic years long domination. Nevermind the fact that last years team finished 10 games out of first and that they would have had to win 12 games over the Braves to make that up and take the division, so you can't single out those games for the failures of 2013. Nevermind they just were in first place despite getting beat up by the Braves earlier in the year, so you have to admit winning the NL East this year, under these conditions, can be done regardless if they win 6 games or 13 versus the Braves*. Nats fans should be able to look past these losses right now, but things like this, they have a way of getting to you.
It's insidious. It gets eyes on the page. It makes for an easy joke, which I'll admit, I'll go after. I'm not above that. It matters, but circumstances have made it not as impactful as it was last year. That's the truth. This year it's really just a battle, not the war.
Tonight is Strasburg. Tony crushed the best Braves. Now it's your turn.
*Now if they win like 1 game - ok talk to me.