Many fans know the Nationals have had the best pitching staff in baseball so far this season. What hasn’t been noticed is that, thanks to Manager Davey Johnson and pitching coach Steve McCatty, the Nats may also have the freshest staff of any contending team.

Nats pitchers dominate most of the major pitching categories. Jordan Zimmermann, Stephen Strasburg and Gio Gonzalez have three of the top dozen ERAs in the National League. Add Edwin Jackson to the list and all four are in the top 20 in Major League Baseball in the least men allowed on base by walk or hit. And if Ross Detwiler had enough innings to quality for leader lists, he’d be 21st in the NL in ERA.

However, in one area they are consistently at the bottom. Compared to pitchers on most teams, the Nats’ hurlers have barely pitched at all. No Nats starter ranks in the top 40 in MLB in number of pitches thrown and no reliever is in the top 40 in appearances. In fact, only one Nat is in the top 65 in pitches thrown.

The 2011 American League Cy Young Award winner Justin Verlander, for example, has thrown 2,032 pitches so far this year — 36 percent more than Jackson, 27 percent more than Strasburg and even 20 percent more than Gonzalez, the Nats’ pitch leader. Since none of them has missed a start, the difference is in how they are used. Or preserved.

This is no accident. “It’s my job not to overwork ’em,” Johnson said, emphasizing the word “job.” Many managers, precisely because they care about their own job, glide lightly over the issue of pitch, inning and appearance restraint. If some pitchers burn out, let the next guy worry about it.

Johnson never worked that way. At 69, he’s even more aware of the fragility of the body and wants to leave a long-term pitching legacy behind him, not a burial ground for shoulders and elbows.

The Nats’ chances to win the NL East and prosper in the postseason hinge almost entirely on the health of their pitching. Few teams keep their arms intact for a whole season; a year without a panicked search for a sixth, seventh or even eighth starter is rare. The Nats have used only six, stashing John Lannan in AAA for emergencies. Except for the absence of Drew Storen, who returns soon, the Nats have missed very little time from any pitcher of significance. In part, that’s luck, which may not continue to hold.

But in large part, the Nats’ durability is the residue of design. The pitch-efficiency teaching of McCatty and the disciplined innings-control decisions by Johnson have contributed to that healthy excellence.

Almost every team shows caution with pitchers, like Strasburg, in their first full year back from a major injury. But once a pitcher has turned 25 and is declared fully healthy, most teams can’t wait to load on the work in those prime 25-to-29 years. All the Nats’ other starters fall in that Young Hoss category. Yet Johnson has handled them all like fine china.

The proof of the Nats’ dedication to arm protection is in the details. The Nats have amassed a best-in-baseball rotation ERA of 3.25. Look at their dazzlingly low rank in innings and pitches thrown by their starters. Zimmermann is 24th in innings (1101 / 3), but challenges hitters so aggressively and efficiently that he’s 69th in pitches (1,635). That may portend a long, productive career. In pitches and innings, Gonzalez (42nd, 61st), Jackson (84th, 63rd) and Strasburg (72nd, 73rd) ought to have signs over their lockers that say, “Do not break glass.”

(Note: The Nats had two rainouts that haven’t been made up yet. Those ended up costing Jackson and Detwiler one start each but don’t significantly change the data.)

One reason the Nats gave Chien-Ming Wang every chance to be the fifth starter was so that, even if he failed in his multiyear comeback attempt, Detwiler could be brought along gradually and still be strong in September and October. Atlanta all-star Michael Bourn described Detwiler’s stuff this week as worthy of a No. 1 or 2 starter in the making. “Man, he can go,” Bourn said.

With Storen hurt (elbow surgery), the bullpen has not been on as luxurious a cruise. Yet the Nats’ main closer and setup man, Tyler Clippard and Sean Burnett, lead the team with 38 appearances — which only ties them for 43rd in baseball. True to form, Johnson remarks constantly about how he doesn’t want to use them even that much and that, with Storen back, he can reduce their workload. Can we just get ’em bullpen lounge chairs?

With Henry Rodriguez’s return from the minors and Ryan Mattheus’s from the disabled list, Johnson may be able to trim the load slightly on Craig Stammen before his hard sinker-slider combination — exceptional all year — loses any of its edge.

Pitchers’ arms were born to ache and break. No usage formula can protect them. When Zimmermann, then Strasburg, required elbow ligament replacement surgery, which sidelined each for a year, neither had been asked to do any particularly heavy duty.

So feel free to invoke any and all charms. Even that may not be enough. But the fact remains that the Nats have handled their staff, right down to the 12th man, with a commitment to a multiyear approach, not a ride-’em-hard-to-win-now approach. The accidental byproduct: exceptional performance in 2012 that makes “win now” possible.

Will the Nats make it to the wire? No one knows. But they’re doing it the right way.

For past columns by Thomas Boswell, visit