The Nationals are on track to host the National League Wild Card Game, and the names and faces that have fueled a likely playoff season are familiar ones. Max Scherzer is again having a Cy Young-caliber year. Anthony Rendon is in the Most Valuable Player conversation. Juan Soto's career is off to a start that is very legitimately historic, and he's only getting better. The rotation has been arguably baseball's best. The bullpen is ... well, the rotation has been very good.

There are a lot of reasons, because there are a lot of talented players on this team. But allow us to shine a light on something you might not have thought about so much: A year after Washington's outfield defense was a clear weakness, it's now a massive strength. They rank No. 1 in Outs Above Average, the Statcast measure of outfield quality. They've had the largest year-over-year improvement in the four years that the metric has existed. They have the largest gap a first-place team has had over a second-place team. They've been ... outstanding.

"Our defense was fantastic today, our outfield defense," said bench coach Chip Hale on Sunday, having stepped in temporarily for manager Dave Martinez while the regular skipper takes time to manage health concerns.

Quite right. If we look at the Outs Above Average leaderboards, you'll see Washington at +24 OAA, which is more than double the +10 of second-place Houston.

That gap between the two -- 14 Outs Above Average -- is the largest we've seen in the admittedly short time frame that Statcast has been tracking. (In 2018, first-place Milwaukee was eight ahead of second-place Atlanta. In 2017, Minnesota was 12 up on Tampa Bay; in 2016, Kansas City held an edge of five outs over the Cubs.)

So: How did they get here -- and how far have they come?

They've helped their pitchers more than any other outfield

That should be obvious from the whole "leading in Outs Above Average" thing, of course. A very good outfield is going to save a lot of outs. But there's more than one way to look at this, too. Let's flip it around from the pitcher's perspective. How much damage has been saved?

Let's look at the difference between actual damage allowed (expressed in Weighted On-Base Average, which is like OBP if it gave more credit to extra bases than singles) and expected damage based on exit velocity and launch angle (Expected wOBA). We'll limit this only to balls in play, so not home runs, and to balls projected to go at least 200 feet, to exclude infielders.

On those balls, Washington pitchers have allowed contact likely to lead to a .443 wOBA, the seventh-highest mark in baseball, yet only somewhat above the Major League average of .431. But despite that .443 expected mark, the actual damage allowed by Washington pitchers has been just a .357 wOBA, tied for the ninth-lowest in baseball.

The difference between those two numbers -- the .443 expected and the .357 actual -- is 86 points of value saved. That's the largest in baseball, just ahead of the Yankees and D-backs. There's some park factor built into this; note that the Rockies rate 30th here. But a lot of this is about defensive skill, and it's worth noting that only two regular starters have been helped more here than Washington's Patrick Corbin.

So, for example, when Jeremy Hellickson allowed J.T. Realmuto to crush a ball at 109.3 mph off the bat on May 3 -- the kind of ball that, combined with its 23 degree exit velocity, is a home run 94 percent of the time -- Michael A. Taylor was there to keep it in.

On Saturday, when Ronald Acu?a Jr. hit a ball at 109.9 mph -- this one the kind of ball that's a homer 86 percent of the time -- V¨ªctor Robles was there.

And in April, here's Robles again, going head-first into the wall in Miami to take away extra bases from Curtis Granderson.

It's the biggest year-to-year increase on record

Again, the "record" here is very short. Statcast came online in 2015, and Outs Above Average is available from 2016 on. We are not talking about a great deal of history. And yet, because the '18 Nationals were a net negative, ranking 26th at -16, there was a lot of room to grow. Grow they have.

+40 -- 2019 Nationals (from -16 OAA to +24)
+30 -- 2018 Pirates (from -13 OAA to +17)
+29 -- 2018 Brewers (from +1 OAA to +30)
+28 -- 2017 Twins (from +6 OAA to +34)
+27 -- 2018 Braves (from -5 OAA to +22)

Those other teams all had pretty clear personnel-based reasons for their improvement. Last year's Pirates had traded away Andrew McCutchen (-2 OAA in 2017) while importing Gold Glove Award winner Corey Dickerson (+10), as well as watched Starling Marte go from -1 to +10. Last year's Brewers added Lorenzo Cain and Christian Yelich; the 2017 Twins had a lot more Byron Buxton; the 2018 Braves traded away Matt Kemp (-17 OAA in 2017).

The Nationals have had their changes, too.

It's a little about Harper being in Philadelphia

Last year, as Bryce Harper neared and reached free agency, an endless amount of digital ink was spilled on the topic of Harper's poor defensive performance. Only four outfielders rated worse in OAA than his -13, and two of them (Daniel Palka, Minors; Rhys Hoskins, first base) don't even play the outfield regularly any longer. That -13, as you can imagine, was a big part of Washington's -16, though as you'll see, it was about a lot more than just Harper.

(In Harper's defense: As we investigated over the winter, his poor defensive play didn't seem to be about lack of skill, just lack of execution. In his first year with Philadelphia, he's improved all the way to +1 OAA.)

It's a lot about Victor Robles

Before there was Soto, there was Robles, who was supposed to be the Nationals' 2018 phenom outfielder after making it to the Majors in '17 at 20 years old and landing a spot on the postseason roster. Unfortunately for Robles, he injured his elbow on April 10, 2018, at Triple-A and didn't make his season debut until Sept. 4.

This year, Robles has been the team's primary center fielder, and while the offensive results have been mixed -- 17 home runs and 25 steals are good, an OPS+ of 91 less so -- his defense has been spectacular. No outfielder in baseball has more Outs Above Average than his +19, and the names below him are basically the defensive legends of our time.

+19 OAA -- Robles, WSN
+14 OAA -- Kevin Kiermaier, TB
+13 OAA -- Lorenzo Cain, MIL
+12 OAA -- Byron Buxton, MIN
+12 OAA -- Harrison Bader, STL

An average outfielder would have been expected to convert 86 percent of the opportunities Robles has received into outs. In reality, Robles has turned 92 percent of his chances into outs -- and the resulting 6 percent value add is tied with Kiermaier and Bader for the best of any qualified outfielder.

For example, on Thursday against Minnesota, Robles laid out to rob Willians Astudillo on a ball with a 40 percent Catch Probability, meaning that this ball drops for a hit more than half the time.

Robles' physical gifts are obvious; he's one of the 30 fastest players in baseball, and he's one of just 10 outfielders to have a tracked throw of at least 100 mph. He actually managed to get two others reaching at least 99.5 mph, and we pause here to allow you to enjoy the folly of Joey Votto attempting to test that arm on a play in August.

As the Washington Post reported earlier this month, Robles -- still a rookie despite that 2017 debut -- has increasingly grown confident in his role as the defensive captain of the outfield. If he's not the best outfielder in the game, it's only because he doesn't have the track record of Buxton, Kiermaier or Cain. He only turned 22 in May; he's very likely a Gold Glove Award winner this year.

It's also about Soto and Adam Eaton improving

Harper aside, the 2018 Nationals had a few issues in the outfield. Eaton and Soto each checked in -6 OAA, giving Washington three of the 17 lowest-ranked qualified outfield defenders.

This year, Eaton has gone from -6 to +1. Soto has gone from -6 to +6. Soto's turnaround of 12 OAA is the third-largest in baseball behind Nicholas Castellanos (-24 to -6) and Harper (-13 to -1). Eaton is just outside the top dozen.

Last month, we dug into Soto's improvement in great depth, detailing how his hard work with Nationals coach Bobby Henley in order to improve his first step has paid off.

"Juan has worked extremely hard on his defense," said Hale on Sunday. "Bobby Henley has done a great job with him. Both he and Victor [Robles] work very hard at it, and even more on the mental side. Where to play, how to approach balls, when to say, 'I can't get him at home, throw the ball into second,' those types of things. It's been improved, and obviously at 20 years old, it's going to get better for him. He's learning every day. It's very impressive."

In Eaton's case, the answer may be as simple as health, hampered as he was for much of last year by a left ankle injury that required in-season surgery. See if you can spot the difference in his annual Sprint Speed, expressed here in percentile form where 100th percentile is elite and 1st percentile is incredibly poor:

2015: 94th percentile
2016: 83rd percentile
2017: 87th percentile
2018: 61st percentile <-- it's this one, this is the one
2019: 81st percentile

That's a serious gap; in 2018, Eaton's top speed was nearly a full foot per second slower (27.5 ft/sec) than it had been in '17 (28.6 ft/sec). Healthy once again this year, Eaton is getting to more balls.

They're improving without Taylor, somehow

The one thing the Nationals outfield defense did have going for them last year was Taylor, who has been with the team since 2014. Last year, Taylor compiled +9 OAA, tied for 14th best; the year before, he had +10 OAA, tied for 10th best. Dating back to '16, his +25 is 16th best, despite the fact he hasn't played nearly as much as several of those ahead of him.

This year, for example, Taylor has taken just 49 plate appearances. After injuring his knee and hip during Spring Training, Taylor was activated on April 8, but he performed so poorly off the bench over the next two months -- .211/.277/.276 through June -- that he was demoted to Double-A on June 28, where he spent the next two months before a Sept. 3 recall.

Because of that, Taylor has barely had a chance to contribute (+1 OAA). But if you'd looked at the 2018 Nationals outfield and were told "it's going to be so much better," you absolutely would not have assumed it would happen without Taylor in the mix.

(The remaining Nationals outfielders, in limited time, have been consistent. Last year's group of Howie Kendrick, Andrew Stevenson, Rafael Bautista and Moises Sierra graded out to 0 OAA, or exactly average. This year, Stephenson and Gerardo Parra have done exactly the same.)

This improvement in the outfield isn't, by itself, changing the narrative of the Washington season. In part due to the implosion of the bullpen (which entered Monday with a 5.91 ERA, the fourth-worst of any bullpen since divisional play began in 1969) and this year's historic home run pace across the Majors, the Nationals haven't actually allowed fewer runs per game than they did last year.

But as far as the outfield goes, there's been a real turnaround here. Last year's poor unit has become this year's best, and it's not just about Harper's departure. It's about Robles, and Soto, and Eaton. Even mostly without Taylor, it's a group effort.