The streets here Wednesday afternoon were crawling with black T-shirts and Pirate caps. The Roberto Clemente Bridge, over the Allegheny River connecting downtown to PNC Park, filled with equal parts beer and hope, which have an interesting relationship to begin with. The novelty of playoff baseball came a year ago, when a two-decade postseason drought was broken. These fans who packed the yard to back their Pittsburgh Pirates weren’t blindly delirious, delivering a civic exhale. They expected more.

And then thick-legged, scruffy-faced Madison Bumgarner took to the mound and all but stared each one of them in the face, at least defiant, probably mean. It is amazing how quiet 40,629 people can be at once. Bumgarner, the left-hander who is the ace of what remains of the San Francisco Giants’ pitching staff, served as a librarian to them all, shushing them until they packed up their reading materials and slouched home, an 8-0 thrashing in the National League wild card game ending their team’s season.

A night after Major League Baseball’s playoffs opened with the absolute mayhem of a 12-inning, 9-8 victory for the Kansas City Royals over the Oakland Athletics, Bumgarner restored order on October’s first day. It was a 3-hour 12-minute reminder that this is not the time of year for chaos. Drama, tension, ulcers? Sure, bring ’em on, and in buckets. But make it orderly.

That’s what a four-hit shutout can do, strip a city of hope, make the march back across the bridge a procession full of murmurs and resignation instead of a celebration of what’s to come. This was a simpler, more streamlined, more accepted postseason story line than the schizophrenia of Kansas City-Oakland.

“It helps when you have that big left-hander on that hill,” veteran right-hander Tim Hudson said. “It makes your job a lot easier as a team.”

Pittsburgh’s postseason run lasts all of one game as Madison Bumgarner and the Giants plow through Pittsburgh on their way to Washington and Game 1 of the NLDS on Friday. (Don Wright/Associated Press)

As win-or-go-home games go, this was about as easy as it gets. That story line: One starting pitcher doesn’t allow a runner to second until the eighth — when he held an eight-run lead — needing all of 109 pitches to calmly complete his work, striking out 10 with one walk. The other starting pitcher (Pittsburgh’s Edinson Volquez) backs himself in a corner (loading the bases with no one out), then makes a crucial error (a poor 1-2 curveball to Giants shortstop Brandon Crawford) that results in catastrophe (a fourth-inning grand slam that broke a scoreless tie).

“After that ball went over the fence, I mean, game over,” Hudson said. “You got ‘Bum’ out there with a four-run lead, the way he was throwing the ball, I didn’t give a damn. We were going to spray some champagne tonight.”

So it is the Giants, winners of the World Series in 2010 and 2012, who advance to take on the Washington Nationals in a National League Division Series that will open Friday in Washington.

Two years ago, many of these same players sat on the tarmac in Cincinnati, winners of a five-game division series against the Reds, waiting to see whether they would fly to Washington to face the Nationals or home to face the St. Louis Cardinals in the National League Championship Series. We know how that turned out. Now, the Giants finally get to D.C.

“I feel really good about it,” Bumgarner said.

The Nats, too, could feel fine. The only team that could rival them as baseball’s hottest headed into the playoffs has been eliminated. The Pirates went 17-6 to end the season. They have perhaps the National League’s most dynamic player in center fielder Andrew McCutchen.

They have pitchers in the eighth and ninth innings who don’t give up runs. They have a city that turns out, all in black and all at once, to back them up. And they are eliminated.

The Post Sports Live crew predicts which unsung hero from the Nationals roster is most likely to have a breakout performance in the postseason. (Post Sports Live/The Washington Post)

Another happy development for the Nationals: Bumgarner would only be able to pitch once in the division series. What he did Wednesday, though, was give a glimpse of what we’re in for in so many cities on so many days this month.

“He did everything we expected of him,” San Francisco Manager Bruce Bochy said.

No, Matt Cain isn’t around for the Giants, out since early August following elbow surgery. And yes, Tim Lincecum is a shell of his former Cy Young-winning self, relegated to the San Francisco bullpen. Even Hudson, Nationals killer that he is, posted an unsightly 8.72 ERA in September.

But with the wild cards out of the way, consider this list: Clayton Kershaw, Jordan Zimmermann, Adam Wainwright, Stephen Strasburg, Zack Greinke, Bumgarner, Lance Lynn and Tanner Roark. Those eight players have two things in common: All are alive in the NL playoffs, and all ranked in the top 11 among NL pitchers in wins above replacement (WAR) for pitchers, according to FanGraphs.

And that doesn’t even get to the American League, where David Price, Max Scherzer, Justin Verlander (just on the Tigers), Chris Tillman and James Shields still lurk. Don’t like WAR as a means of evaluating pitchers?

Throw in the Royals’ Yordano Ventura and the Nationals’ Doug Fister as top 10 in their respective leagues in ERA. That’s an all-star team of starting pitchers, all alive in October, each able to author silence in an opposing city, joy in his own.

“That’s what wins,” Crawford said.

When Bumgarner hit for himself in the top of the eighth, the crowd managed a few feeble boos at the sound of his name over the public address system. He worked around an error and a single, and Bochy had closer Sergio Romo warm for the ninth.

No chance.

“He gave this look like, ‘No, no, I ain’t coming out of this game,’ ” Bochy said.

It is what pitchers of his stature do at this time of year. “Maybe there’s a little bit of me being selfish wanting to be out there and get the complete game,” Bumgarner said.

By the time he came out to work the ninth, the stands were emptying. The Clemente Bridge filled again with people, still wearing black, still backing the Bucs. But by then, they had no more expectations for 2014. Madison Bumgarner had stripped them away, and for a night, the postseason looked like the postseason again.