The Nats are sneaky. The Nats are sly. They seem to have more identities than Jason Bourne. Just when you think you’ve nailed them down and know their limits, they pull out a new passport. For the past 85 games, more than half a season, they’ve scored more runs than any team in baseball.

That can’t be possible. It must be an unsustainable fluke. But it isn’t. Offense is the camouflaged reason the Washington Nationals have baseball’s best record as well as excellent postseason prospects even without Stephen Strasburg.

Since he took over in June 2011, Manager Davey Johnson looked at the Nats and saw more than just a respectable lineup when healthy. Johnson saw an elite attack, reminiscent of his 1980s New York Mets and 1990s Baltimore Orioles, which was just waiting to jell.

Oh, Davey, you old con man, you’re just trying to pump up your young players. You can’t really believe that. Yet every time he has been pressed, he maintained he saw a deep lineup with power in every spot, enough speed to complement that thump and right-left balance that should raise unholy hell.

And it looks like he was right again. For the past three months, the Nats have averaged 5.24 runs per game. Before that, they averaged just 3.73 in their first 71 games. Which is closer to reality? We know what Johnson believes. When are we going to believe him?

The Nats roused when Michael Morse returned after missing 50 games because of injury. Then they ignited in late June when Ryan Zimmerman got a cortisone shot in his aching shoulder and went on a tear. Finally, in August, Jayson Werth and Ian Desmond returned from the disabled list. Davey had all his pieces, but what was the proper batting order sequence to unlock their synergies?

Werth suggested he become baseball’s only 6-foot-5 leadoff hitter. His left wrist might not get its full power back until next season, but he could still get on base (.410 on-base percentage since returning), wear out pitchers and run.

Johnson, who loves to think outside the box, realized that a lineup that began with Werth and 19-year-old Bryce Harper, would make a statement about the Nats’ hostile, aggressive intentions. The best lineups set a tone and even induce some fear. Werth and Harper embody a type of unapologetic power-plus-speed swagger. If the faux-hawk teen and the werewolf were not a matched pair of cold stares, who would be?

Behind them comes a pair of polished proven RBI men in Zimmerman and smooth Adam LaRoche. Neither is as good as the best 3-4 hitters. But they are comfortable with the pressure of those spots. LaRoche has been so at ease that he usually hits fourth now, even against left-handers.

The real trick of the thing, however, was that the Nats’ four best on-base-percentage men, and their most patient hitters, now batted 1-2-3-4. They functioned as a unit, forcing pitchers to work hard while they observed the pitcher’s patterns. As a group, they were both threatening and annoying. All four can hit the ball through the right side, opening up first-to-third chances.

By a quirk, this opening sequence allowed Johnson to bat the club’s three high-extra-base-hit, high-strikeout players — Morse, Desmond and Danny Espinosa — in the 5-6-7 spots. Lower in the lineup, they could do what they like best: Arrive at the plate with men on base, then wail away, free of the demands of conscience or plate discipline. Motto: do damage.

When hitting coach Rick Eckstein and Johnson got catcher Kurt Suzuki sorted out, the lineup was eight deep. Seldom do fifth, sixth and seventh hitters have such protection behind them. As a result, the bottom of the Nats’ order causes far more trouble than most N.L. teams.

Never underestimate how far ahead Johnson is. Why do the Nats pull off so many successful double steals? Because Johnson pairs off his four best thieves — Werth and Harper at the top of the lineup and Desmond and Espinosa back-to-back at No. 6 and 7 — so they can steal in tandem. Johnson also loves the right-left-right-left-right-right-switch-hitter sequence of his order. It makes late-inning bullpen moves against the Nats less effective.

The current lineup produces because, when healthy, it makes up in relentlessness what it lacks in star power.The Nats have no great hitters. None is in the top 10 in MLB in any important offensive stat. Yet consider: The first five Nats hitters have all had seasons with at least 31 homers, except Harper, who has 21 already at age 19. Behind those imposing men are Desmond, with 25 homers this year despite missing a month, and Espinosa, who has had 55 extra-base hits in ’11 and again in ’12.

None is terrifying, but each is a concern. The Mets’ R.A. Dickey, a Cy Young hopeful, said the Nats, more than any team he faced, made every pitch stressful.

It’s tempting to think the Nats have just been hot for three months, that this tear is a bit indicative of their genuine ability. Maybe. But no Nat, except Desmond, is having a career year. Morse and Werth have had much better seasons.

If the Nats have a secret sauce, it’s their Goon Squad, led by Chad Tracy, Roger Bernadina, Steve Lombardozzi and Tyler Moore. The Nationals’ reserves are having one of the best bench seasons in 40 years. That’s a Johnson pet project, too.

When the postseason starts, we’ll be told the Nats will go as far as their pitching will take them — with that big haunting Strasburg asterisk. That will sound right at first glance. And since the All-Star Game, the Nats do have the game’s third-best team ERA.

But from June 27 through Sept. 27, the Nats have been the No. 1 scoring offense in baseball. And they lead by a clear margin, despite playing in a league without a designated hitter.

If the Nats really do have a lineup that has become, even roughly speaking, as good as Josh Hamilton’s Texas Rangers or the 233-homer New York Yankees, then we might once again be in danger of underestimating the Nats. They keep changing who they are. Every time we catch up, they look a little better.

For Thomas Boswell’s previous columns go to