Gio Gonzalez struggled Sunday, and the Nationals suffered a demoralizing 12-1 loss to the last-place Marlins. (John McDonnell/The Washington Post)

Whistling past the graveyard beats being in it.

So the Washington Nationals have been whistling for 125 games. Can’t blame them. But the sound you hear now is silence. All that’s left, after 10 horrible days in which the Nats squandered four games they should have won, is a brief note from the team telling its fans where to send the wreaths and condolence notes.

The culmination of this hardball catastrophe was a 12-1 loss Sunday in which the inert, demoralized Nats were stunned like mackerel by the miserable Miami Marlins. A Miami team in tear-down mode that had gone 2-15 entering play Saturday beat the Nats back-to-back just when Washington needed momentum most.

For many weeks, the Nats have circled Tuesday, Aug. 21 on their schedule as the beginning of a 10-day stretch, including six games against the Philadelphia Phillies, in which their team would begin its last great stand of 2018 and prove itself. The team that has won so many games over the past seven seasons but that certainly will be scattered soon with 10 players in their walk year, said over and over that it would start “playing the way we can” and show ’em all.

Every decision was pointed toward that crisis date. That’s when every injury, bad play and bad break would start reversing. That’s when the hot streak would start. On Sunday, the Nats announced that Stephen Strasburg, out since June 8 except for one appearance, will start against the Phillies on Wednesday. Tanner Roark, on a five-game winning streak, goes Tuesday with Max Scherzer, working on a fourth Cy Young Award (or a first MVP award), on Thursday — perhaps going for a sweep.

Nationals Manager Dave Martinez, right, has had few answers as Washington’s season continues to spiral. (John McDonnell/The Washington Post)

That’s the way the Nats had it planned out in their defiant scenarios. Except that in the past 10 days, their season probably has died of self-inflicted wounds.

In Chicago on Aug. 10, they lost a one-run game in which at one point they held an 80 percent win expectancy. Good teams only lose a handful of such games a year. But the Nats were just getting started — in reverse. Two days later, they lost, 4-3, on a walk-off grand slam by an obscure pinch hitter who was down to the game’s last strike. That hadn’t happened in the majors in 79 years.

The next night in St. Louis, they held another winning hand — this time not 98 percent probability but 92 percent — and they blew that, too, on a walk-off homer against Koda Glover, the symbol of an utterly shredded and depleted bullpen.

In the universe of arithmetic, the Nats are still alive, but there is no baseball played there.

The Nats, with 37 games left, should be at the start of a six-week playoff race right now, trailing the Phillies and Atlanta Braves by about four games — certainly within range. But they aren’t. Because every time they have a precious chance to make up ground, they play their worst. So they enter Monday seven games behind the Braves and 6½ behind the Phillies in the NL East.

The Nats’ playoff deficit is worse than that when you include their slim wild-card chances. Six teams are ahead of Washington in that chase for only two spots.

To their credit, many Nats remain publicly defiant. They remember that the 2007 New York Mets, who had won 97 games the previous season, blew a seven-game lead with only 17 to play. In 2011, the Braves and Boston Red Sox missed the playoffs after mind-blowing 8-18 and 7-20 collapses to get eliminated in game No. 162.

The only time that a Washington team won a World Series, in 1924, the Senators were in third place behind Babe Ruth’s New York Yankees and Ty Cobb’s Detroit Tigers on Sunday’s date. Then they went 26-10 to win the pennant.

“I like that. That’s sweet,” Bryce Harper said before Sunday’s game. Then he went out and misplayed three balls in center field, costing three runs.

Afterward, Harper conceded that in his seven seasons with the Nationals, the team had never absorbed this many gut-punch losses in such a short time. “No, [we haven’t],” he said. “We’ve always been ahead at this time — super far.

“The next couple of weeks are going to be hard. But a lot of us are looking forward to it,” Harper said of the challenge. “But it’s going to be tough.”

It will be murder if they stink like they did Sunday. The Phillies must be terrified.

“It was an ugly game, and everybody saw it. I want to forget about this one,” Manager Dave Martinez said. That may be hard. Especially because the previous Nationals manager, with 1,863 career wins, broke his silence this past week.

Somewhere, perhaps on his back porch in California, Dusty Baker may have used his Sunday evening to decide between a gentle pinot noir and a more robust merlot, possibly one chosen from his own vineyard. If his phone rang, maybe it was Carlos Santana, the Woodstock legend, not the Phillies first baseman.

Baker said this past week that he empathized with his former Nats players but not with “the front office.” So Baker probably felt a tad sad when he learned of the 12-1 drubbing and that Gio Gonzalez, who flourished under him, has a 1-5 record and 6.39 ERA in his past seven starts. But the Nats’ plight must also bring him a sense of vindication at the current discomfort in the world of the Lerners, the family that didn’t want him back. And then let the general manager inform him by phone.

But if Baker is as wise as most of his old friends think he is, he will end his day with a big, cosmic belly laugh as he realizes that he escaped managing this mess.

In the spring, the Nats’ everyday lineup was in shambles because of major injuries to half of the projected starters. Remember Moises Sierra, Andrew Stevenson and Pedro Severino? As starters healed, the pitching rotation imploded after a Strasburg injury in early June. Who knew Tommy Milone and Jefry Rodriguez would be starters? Now three of the Nats’ top four relievers are on the disabled list (Sean Doolittle, Ryan Madson and Kelvin Herrera) while the fourth, Brandon Kintzler, was traded, in part, because he was too honest with his skeptical quotes. If Baker took truth serum, would he honestly think he would have won the division with this hand and against much improved foes?

Baker will be recalled as the fine manager who won 192 games his last two regular seasons. Dignity, it’s good. The current Nats wouldn’t know about that. Almost all of theirs has been stripped during these first 125 games in which they are a losing team — 62-63. The main reason is a 12-21 record in one-run games. Under Baker, the Nats’ record in such games was 56-40 — a 95-win pace.

For context, as well as shock value, it’s useful to recall that this team was so ultra-confident that Martinez had players practice home run trots and walk-off celebrations in spring training, as well as holding golf shot contests.

They worked on drills plenty, too, and have the second-best fielding percentage in baseball. But all in all, they have been a slipshod, blundering bunch. “Humps,” it has turned out, have been the very things they seldom get over. Thus, as if worse news were needed, this season has also been a great disappointment to camels.