Read the comments and you'll see fans are torn. Trade something worthwhile for Zobrist? Yes! Be as good as you can be! No! Don't rent a guy for a year when the Nats are favorites without him!
The math is fairly simple. If you can improve your odds of winning enough then you can have a better chance to win over X playoff appearances than X+1, but it's tough to improve them by that much (and that consistently). It makes far more sense to try to maximize appearances then, which is what the Nats seem to be doing. Be a perennial contender. Let the championships fall where they may.
It's that last point that sticks, though. Championships are not guaranteed things going to the best team every year, or the hottest team, or the most "teamy" team. They go to some combination of the before in a formula so dominated by game to game luck that it's probably meaningless to do anything more than get in with a solid squad.
But it's that word "probably" that gets me. It's "probably" meaningless. But what if it isn't? This is why, despite all the logic saying "don't bother", that teams try to improve all the way to the bitter end. It doesn't matter... until it does. Getting that 2nd lefty in the pen is a waste, until you need him in the 10th inning of a tie game. Picking up that 5th OF speedster is superfluous, until your lumbering slugger is walked in the 8th and you're down by one, The Nats are no different. Picking up Asdrubal Cabrera was doubtful to be the difference maker, but they could do it and it would make the team better so why not?
We also labor under the false pretense that post-season appearances are just going to keep coming. The NL East looks pretty beatable again with the Braves heading down and the Mets and Marlins not improved enough on paper. But it wasn't so long ago that a team suddenly went from .500 to 98 wins in the NL East. And it wasn't so long ago that that almost 100 win team missed the playoffs thanks to injury and a terrible bench (I'm sorry - because they tried too hard but didn't try hard enough or some clap trap).
Here's a scenario for you. Cuddyer is good. Harvey is good. The Mets make another move. The Mets are a 90 win team. Stanton is MVP again. Jose Fernandez is BACK and Latos is good. Prado is Prado. The Marlins are a 90 win team. Rendon gets hurt. Werth gets hurt. Gio gets hurt. Roark falters. The Nats are a 90 win team. The Nats gets squeaked out of the playoffs. ZNN walks. Desi walks. Fister walks. Clip walks. Rizzo deals Stras for something for 2018. Likely? No. Plausible? Yes.
There are no guarantees. This is what pushes the all-in mentality more than anything. Tomorrows aren't set in stone. Giolito is a year away, but a year away from what? Major league dominance or another injury for an arm that couldn't stay healthy pitching to high schoolers? You need 6 playoff appearances to get to the point where winning one is more likely than not. SIX. You could win more than one in those 6 but it's just at that point where you get to "you should have won at least one by now". Six is a lot.
This above - this is first world problems. Does a team sacrifice some of an apparently bright future for a slightly (ever so) brighter today? The truth is there isn't a good answer. You either make good and fair deals (I think Cole for Zobrist would qualify - Cole+Taylor or Giolito wouldn't) or you stay the course. Either way what will ultimately decide if you were right is going to be the number of titles you bring home. Right or wrong that's the way it is. Because while we can say "make the playoffs then get lucky that's all you can do" in truth we can't prove that's all you can do and that will nag and claw at the soul if you end up hands empty years down the road.