The Illustrated Playoff History of Atlanta United is a brief tome. But being set in Atlanta, you know that even this virtual pamphlet had to contain a high concentration of bitter dregs.

Sunday, though, was an entirely new chapter. The second-year soccer team won a playoff game for the first time at home, and won it resoundingly. In the process, it also won its first-ever playoff series.

It even scored multiple goals over the course of regulation time – in every way, penalty shot, free kick and a full-bore Josef Martinez blast – another playoff first inside Mercedes-Benz.

You must give Atlanta United credit for the way it went about dispatching New York City FC in the conference semifinal. Really, you must. Even if you consider soccer some sort of international conspiracy.

Coming into this second and final leg of the series with a game in hand and a one-goal advantage in this aggregate goal format, Atlanta United could have chosen to play a little high-level keep-away Sunday. It could have gone all conservative, trying to protect the lead rather than build upon it. But that’s not Atlanta United. Instead, it stayed true to the identity it began forming from Day One, coming out and pressing the action and, you know, keeping stuff interesting.

The 3-1 victory over NYCFC Sunday – completing the playoff sweep – was anything but careful and conservative.

And along the way, the match confirmed pretty much every preconception held by the noisy rabble of 70,526 inside the Benz: That Atlanta United was the far more skilled of the two teams and that NYCFC was a troupe of ruffians and bad actors and whiners who deserved to be relentlessly booed.

Playoff soccer, the worldly and erudite Atlanta audience already has learned, is different from your everyday soccer. Playoff soccer is medium rare – cool and a bit bloody at the center. Regular soccer, especially in the MLS, where seasons last so long they really should be called regimes, couldn’t possibly stomach that kind of thing over such a long haul.

“It’s completely different,” confirmed midfielder Greg Garza. “Very intense games, it’s a different tournament. You kind of turn the page on what everything was from the regular season. You could probably say the same thing in every sport. It’s a different league onto itself.”

Playoff soccer is hard, darn hard. Atlanta United learned that a year ago when its surprisingly vigorous inaugural season abruptly ended with a one-game knockout loss to Columbus at home. Yes, another bitter Atlanta playoff loss, a game far more exciting than the 0-0 score at the end of regulation indicated. United’s fate was thrown to the fickle winds of penalty kicks, and there it was blown away.

Atlanta United took all luck and chance out of the equation Sunday. It ran around and through this stage of the postseason.

There will be no such sudden pulling of the plug just yet. Winning and advancing Sunday, the Five Stripes have gone the necessary one more step than a year ago. They’re still trending.

The forecast for Sunday’s game was for aggression with a chance of contusion. Yes, believe it or not, soccer can be a rough game. And playoff soccer is supposed to bring out the best and the beast in teams.

Atlanta United’s fleet midfielder Miguel Almiron was the target for much of NYCFC’s bad intent, if for no other reason than he is the most frustrating player for an opponent to chase. “As a player, you have to get used to that,” he said of the rough stuff. And certainly, it was the threat of Almiron’s great speed that provoked the first yellow card on a NYCFC defender who chopped him down in front of his own bench.

The 24th minute featured a field littered with writhing bodies – midfield, front and side of the NYCFC goal - until finally a penalty had to be called when Franco Escobar was taken down by NYCFC’s Ismael Tajouri-Shradi. Enter Mr. Golden Boot, the MLS’s record-setting goal scorer, Martinez. His was a particularly graceful penalty kick, with a couple mesmerizing dance steps and one big hop before he deposited the first goal into the net.

We’d like to ask him about that move, but in this post-game like most others, Martinez declined to talk after his brief ESPN interview. He lets others carry that responsibility.

Anyway, drawing a second yellow card 41 minutes into the match, Almiron had the pleasure of bending a free kick from 25 yards out into the upper corner of the New York netting to make it 2-0 United.

All the right people put their signature on this breakthrough first playoff victory.

Goalkeeper Brad Guzan didn’t have it as easy as the first game of this series, when NYCFC got nary a shot on goal. Atlanta United even yielded a goal this day, but it could have been more had Guzan not channeled his inner big cat.

And it was Almiron and Martinez, the engines of this team all season, who provided all the scoring.

Throw in a little depth - Miles Robinson made his first start since May and helped shut down New York’s leading goal-scorer David Villa - and you have the elements of a serious playoff team.

And don’t forget the attitude either.

“Coming into the playoffs we wanted to show we were a totally different team (from the one that badly lost its last game of the regular season),” midfielder Julian Gressel said. “We had to show a different face the last two games and we showed that.”

And that face was ... ?

“A little more gritty, hard working,” Gressel said. “A lot of intensity, a lot of hard work, against the ball, with the ball. Have at least that on the field. You can play a bad pass, have bad moments but that’s what we wanted to show that (toughness) first and quality comes through that.”

Point proven. Atlanta now will travel to New York to begin the away-and-home, two-game conference final Nov. 25. They’ll face a Red Bulls team that compiled the best record in MLS this season, and beat United 2-0 in late September.

A tall order. But more playoff activity inside Mercedes-Benz is guaranteed this season. A full house and grateful team will commune again.

“Last year it didn’t end the way we wanted it to and the fans were still chanting their tails off. We definitely owe it to them,” Garza said.

Given what the Benz’s other tenant did earlier Sunday up in Cleveland, no other playoff moments beneath the flower petal roof loom.