I'll admit that possibly the bigger part of the reason I wanted the Nats to beat the Cubs is not because of some psychological advantage (though I do think that can be real) but because I didn't want to hear about that possible psychological advantage constantly leading up to the playoffs and a possible series. It could matter like I said but it wouldn't be treated as one of a number of possible impactful items. It would be treated like the number one important thing going in and would stay that as long as it continues. So it's dead. Good. I suppose if the Cubs trash the Nats the next two games it may pop up but I'll worry about that then.
Trea Turner did apparently have an effect by being called up. Since he got sent down Danny Espinosa has been on fire. .385 / .448 / .808 in 7 games. Three multi-hit games when he had 7 in his first 55. Stephen Drew isn't slacking either. .500 with 2 homers and a double in 12 ABs. Is this really about Trea? Probably not, but it's nice to have the motivating factor of players on your tail.
This kind of motivation might extend to other players too. Ben Revere can't struggle for too long because MAT is there looking for another go, getting solid play in favorable conditions. MAT can't struggle for too long or he may not get to play. Jayson Werth can't struggle for long because they might go in a different direction come trade deadline. This is all armchair psychology but there can be more than just the most important "capable players ready on the bench" benefit to having a quality bench.
The Nats offense is rolling and that means that Zimm, who is like the only Nats really struggling recently, can have all the time he needs to get better. The Nats can ride out the inevitable rough patch** with the starters. The Nats can figure out exactly what they want to do with the back end of the pen. A good team has the luxury of time, because they don't ever fall too far out of where they want to be. The healthy Nats are a good team.
Better yet, the unhealthy Mets may not be.
Another thing to note - which is a surprise to me - is that the Nats have found their identity offensively. They are a homer hitting team. Six players with 9 or more home runs right now which translates to 6 or more 20 HR hitters. Drew and Heisey have been HR threats off the bench, as is MAT I'm sure. The Nats are 7th in BA, 9th in OBP, which keeps them from being a crazy special offense and also notes that that isn't who they are. They are bashers. Homers in 15 of 16 last games.
Power pitching. Homer bashing. Fun team right?
*It may not even exist. Though I don't really believe that.
** In that these patches happen to all teams, even ones with superior rotations like the Nats. You'd need like 4 number ones to really not have a rough patch come up.