New Manager Davey Johnson is full of ideas on how to tinker with the Nationals, particularly the pitching staff, and the second half of the season will show if his actions work out or send the team into another late-season tailspin. (John McDonnell/The Washington Post)

Since their first season in Washington, the Nationals have faced the normal stress tests that teams confront every season: injuries, slumps, controversies, kids who flop, vets who get old. Each year the first cracks in the foundation have led to collapse. Pick a number from 89 to 103. That’s where the defeats stopped.

So far this year, the Nats have been under enough weight to crash a suspension bridge. Their best player, Ryan Zimmerman, missed two months. Their 100-RBI free agent Adam LaRoche played hurt, killed rallies for seven weeks and then went out for the season. Mega free agent Jayson Werth reaches the all-star break hitting .215 and, oh, the manager quit minutes after a game.

Yet after their 2-0 win over Colorado Sunday, which snapped a three-game losing streak, the Nats reached the all-star break at 46-46. How would Nats of the past have coped with ’11? “Are you kidding?” said Zimmerman, rolling his eyes. “We’ve gone through a lot to be where we are. It’s great. It shows the team we have.”

Pointing out that he and Werth haven’t really produced, Zimmerman added: “Let us get going. Look at the [89-win] Padres last year. Crazy things can happen.”

So, the Nats will spend four days with their chests out. “The resiliency of this team is as good as any team I’ve been around, including the ’01 Diamondbacks,” said General Manager Mike Rizzo, referring to that season’s World Series winners.

Almost all of the team’s major story lines, except Werth, have worked out good-to-best-case. Rookies Danny Espinosa and Wilson Ramos have locked down second base and catcher. If slumping Ian Desmond hits anything like he did in ’10, his improved defense will entrench him at shortstop. It’s time to put Michael Morse in the frame too. As a Nat, he’s hit .295 in 589 at bats with 33 homers and 100 RBI. That was hoped of Werth. Mr. Morse has come to Washington and he’s going to stay and play, somewhere.

“To start the year, we had questions at catcher, second base, shortstop, center field and left field,” said Manager Davey Johnson. “Now we are getting the answers. This year is really important for establishing young players at a lot of crucial positions all at once.

“This [process] is not a new animal for me,” he said. “You take a few knocks early but the byproduct is winning.”

For the future, Stephen Strasburg is throwing full force. Can starts in the minors be far away? Bryce Harper’s smooched his way to AA.

But there are clouds, plenty of clouds. You don’t think stress tests ever stop, do you? One of them actually concerns Johnson. He’s not managing to keep his job. Rather, he’s trying to redefine several roles simultaneously so that he can rework the roster to where he thinks it should be next year — “for whoever the manager is.” In theory, that sounds good, but in practice it’s been bumpy.

In just two weeks, Johnson has enlarged the roles of relievers Ryan Mattheus and Henry Rodriguez while arm-wrestling Rizzo into keeping Ross Detwiler in the majors as his “sixth starter” and long reliever. He wants to identify a right-handed long-reliever, too. Five starters, five short relievers and right-left long men. He’s also given Roger Bernadina a starting job in center and made Brian Bixler a super-sub. That’s a lot of flux for a team that was hot. Will he destabilize a good thing in the short term for eventual gains?

Two recent losses may have been a by-product of Johnson being “handcuffed” because he was trying to fundamentally change the bullpen so that, long term, Drew Storen and Tyler Clippard aren’t burned up the way Chad Cordero once was.

“For a couple of weeks, I’ve been rolling the dice. I’ve done things I don’t like to do. I haven’t been comfortable with where we are. And I’m not there yet. But it’s getting closer,” said Johnson, who admits he mismanaged an 8-0 lead to the lousy Cubs that became a 10-9 loss. “That three-run homer [off Livan Hernandez to make the score 8-6] can’t happen. . . . I screwed up.”

The explanation is novel. Basically, Davey never jerks players around without explaining what’s up. He forgot to tell Sean Burnett he might be used earlier in the game than normal because the pen was toast. But he forgot. When Livan got in trouble, Davey tried to ride it out without using Burnett. It didn’t work — big time.

The Nats’ starting rotation, a shockingly unexpected strength all year, will face the most severe second-half stress test. The brightest light of the season, Jordan Zimmermann, lowered his ERA to 2.66 with 6 1 / 3 innings in his win Sunday. Except for a misplayed fly ball in his previous start, he’d now have 15 straight quality starts. He’s on the verge of stardom. He’s also on the verge of being shut down for the rest of the season, as a precaution after elbow surgery, after just 45 more innings or about eight more starts.

On top of that, here comes the trade deadline. By July 31, the Nats may, if they get good enough offers, trade Jason Marquis (7-4, 4.05) or Hernandez (5-8, 4.01). “They are worth a lot to me,” Rizzo said. “Those are a lot of quality starts we can count on.” But, he adds, “We have three or four more talented arms in the minors that could be in the majors right now.”

Zimmermann going? Marquis or Livo conceivably gone, too? Could they really be replaced? Hold on tight. Believe it or not, Chien-Ming Wang, if he keeps up his progress in the minors, will be in the majors this month because the Nats have to use him by then or lose him. “Why wouldn’t he?” Rizzo said. Color me incredulous.

One arm Rizzo praises is lefty Tom Milone, 24, who has a 107-to-7 strikeouts-to-walks ratio at Class AAA. On Sunday, hot Brad Peacock was also summoned to Syracuse after torching Class AA with near-Strasburg stats. When a 41st-round draft choice matures at 23, then changes his arm slot (over the top) and suddenly dominates everybody, you wonder, “Is this a movie?” Cheer. Or cross fingers.

In just a few days, the Nats, who have already absorbed a season’s worth of major miseries, will start to find out whether they can adapt to Davey’s tinkering and survive the possible reworking of their rotation.

Are those cracks we’ll start to see? Or will the Nats, as they have done all season, respond to the heavy lifting by getting stronger? Until then, they have four days off. Rest. You’ll need it.