MORRISSEY: Have the Cubs put a curse on the Nationals?

Nationals pitcher Stephen Strasburg stands in the outfield during practice at Wrigley Field on Sunday. (AP Photo/David Banks)

Bad things used to happen to the Cubs — as a rule, on general principle and just because.

But’s that not how the Cubs roll anymore, and if last year’s World Series title wasn’t enough proof for you — and why isn’t it? — their first-round series with the Nationals is offering additional evidence.

Game 4 was rained out Tuesday, giving the Nationals every opportunity to start ace Stephen Strasburg on full rest Wednesday. Except for one problem: Nats manager Dusty Baker said Tuesday evening that Strasburg was “under the weather” and would not be available to pitch Wednesday.

Strasburg’s troubles were caused by “change of weather,” “air conditioning in the hotel” and “mold around Chicago,” Baker said.

The Cubs had the Billy Goat Curse. Do the Nationals have the Moldy Air Duct Curse?

If what Baker says is true, it means Jake Arrieta will face the Nationals’ Tanner Roark at Wrigley Field on Wednesday. The Cubs love everything about that matchup and the chance to advance to the National League Championship Series.

You don’t need a weatherman to know which way the wind blows for the Cubs. It’s at their backs. Especially in this series.

In Game 2, a Cubs fan reached out for a baseball and didn’t have to go into permanent hiding afterward. That’s because a video review showed that Anthony Rizzo’s home run had cleared the right-field wall before the fan got a hand on it. So no Bartman redux.

In Game 3, Cubs left fielder Kyle Schwarber committed not one but two errors on a dropped fly ball, allowing Daniel Murphy to get all the way to third base. Ryan Zimmerman doubled him in to give the Nationals a 1-0 lead in an intense pitcher’s duel.

Oh, and the Cubs won anyway. In fact, they committed four errors, got only four hits and won.

You can argue the Nationals are acting like the Cubs used to act, if you want to get really cruel about it. In Game 1, Nats third baseman Anthony Rendon dropped a ground ball, allowing a rare baserunner off Strasburg, leading to the Cubs’ first run. It was the sort of thing that used to happen to the Cubs on a regular basis.

They’re not the haunted anymore. They’re the haunters.

The Cubs believe the gloriously ugly Game 3 victory showed everything that’s good about them.

“That just says a lot about our team,” pitcher Kyle Hendricks said. “It’s kind of what we’ve been doing all year. Goes back to last year, even. This group of guys, they just never quit. Just put together good at-bats, no matter what had happened previous in the game.”

The Cubs are up 2-1 in this division series not because they’re the better team but because they’re making things happen when things absolutely need to happen. Do they want it more than the Nationals? Hard to believe that. Hendricks said the Cubs never quit. It’s also hard to believe that the Nationals, a 97-victory team in the regular season, ever quit, either.

But maybe there’s something bigger here that can’t be quantified. Cubs president Theo Epstein believes there is.

“I know some people roll their eyes at this, but I think our players are in the midst of carving an identity for themselves that revolves around playing calm, confident baseball when it matters most and being able to stop some things and remain confident in the face of adversity,” he said.

Kris Bryant and Rizzo have an air about them that says good things are at hand. It says the more important the moment, the more likely the good will happen. It says that this is their time and that they’re having the time of their lives.

“The front office has done such a good job of putting the personalities together in the clubhouse,” Hendricks said. “Everybody, the focus is on winning no matter what. KB and Rizz are two of the best. The win-at-all-costs [attitude], really. And it’s just giving that last extra ounce that maybe the other guy wouldn’t.

“Something about the personalities, I think, that’s put together in that clubhouse, it’s just a special feeling, and guys are going to get behind each other and pick it up no matter what has to be done, really, just to win. That’s the bottom line.”

The other day, a reporter asked Jon Lester if a negative storyline — the Billy Goat Curse for the Cubs, no playoff series victories for the Nationals — can seep into a clubhouse.

“You know, on their side, I don’t know if it’s in their head,” he said. “I mean, I know for us, every day, you heard about a goat or you heard about Bartman or you heard about the black cat or 1908 or whatever else you heard about. You’ve got to eliminate that stuff and go out and play the game. The game does not change.”

The weather does, though. And you’re supposed to change your air-duct filter every 90 days.

Follow me on Twitter @MorrisseyCST.

Email: rmorrissey@suntimes.com