The last time Buck Showalter managed a playoff game, he ended up on the hot seat after an agonizing loss for Baltimore.

Six years later, a shot at redemption begins Friday with the New York Mets.

The popular Showalter takes his fourth franchise to the postseason this weekend when the Mets host San Diego in their best-of-three wild card series. The veteran skipper has spent more than two decades pacing major league dugouts and is still seeking his first World Series appearance.

“He's got that chance — and that's really what you come back for,” said former teammate Don Mattingly, who just stepped down as manager of the Miami Marlins.

Showalter had baseball's best closer with the Orioles in 2016, but didn't bring Zack Britton into their wild card loss at Toronto. Waiting for a save opportunity that never developed, Britton was left in the bullpen watching helplessly as Ubaldo Jiménez gave up a three-run homer to Edwin Encarnación in the 11th inning that eliminated Baltimore.

A well-respected Showalter was roundly skewered by fans, writers and commentators. He guided the Orioles through two miserable seasons that followed, then spent three on the sidelines doing television work.

Now, he's back on the bench in October after winning a career-high 101 games in his first year leading the Mets. He joins Yogi Berra as the only managers to take the Yankees and Mets to the playoffs.

“I’d like to say that I’ve evolved with what the players need,” Showalter said. “You roll up your sleeves and see what they need you to bring, and you try to bring it.”

The only other managers to reach the playoffs with four organizations are Billy Martin, Davey Johnson and Dusty Baker (five teams). The 66-year-old Showalter, however, is the lone member of that quartet without a pennant.

And his postseason history is a painful pattern of what might have been.

A whiz kid across town, Showalter was just 38 in 1994 when players went on strike that August. At the time, his New York Yankees held the best record in the American League — but they were denied a chance to chase a ring when Major League Baseball later canceled the postseason.

The next year, he piloted the Yankees to their first playoff berth in 14 years. But they blew a 2-0 lead in the best-of-five Division Series with three straight losses in Seattle, dropping the decisive Game 5 in 11 innings on a two-run double by Hall of Famer Edgar Martinez.

Late owner George Steinbrenner wanted to fire several coaches, and when Showalter wouldn't swallow that, he was gone, too.

Joe Torre replaced him and managed the Yankees to their most recent dynasty on his way to the Hall of Fame, winning the 1996 World Series and three straight from 1998-2000 with several core players Showalter helped to groom.

“I think he’s pretty perceptive,” Mets reliever Trevor May said. “He knows a lot about guys before he even manages them.”

After leaving the Yankees, Showalter hooked on with expansion Arizona and called plenty of shots as the entire organization started from scratch.

In their second season, he managed the Diamondbacks to 100 wins and the 1999 NL West title before losing to the Mets in the playoffs on a series-ending homer in the 10th inning by backup catcher Todd Pratt, subbing for injured Hall of Famer Mike Piazza.

Two years later, Arizona won the World Series under Bob Brenly, beating the Yankees in a seven-game classic.

Showalter and the Orioles pushed the Yankees to Game 5 in a 2012 Division Series, then won the AL East in 2014 at 96-66 to earn him the third of his three AL Manager of the Year awards in a 20-year span.

But the Orioles ran into a red-hot Kansas City Royals squad that swept Baltimore in his only League Championship Series appearance.

Then came the Britton episode in 2016 — also the last year the Mets made the playoffs before Showalter arrived.

“Guys love playing for him,” big league batting champion Jeff McNeil said. “Definitely want to win one for him.”

In an interesting bit of symmetry, Showalter again has arguably the most dominant closer in baseball this season in right-hander Edwin Díaz.

But those 101 wins — second-most in franchise history — only earned the Mets (101-61) the top National League wild card. A division crown slipped away when they were swept last weekend at Atlanta, which came from 10 1/2 games back on June 1 and seven behind on Aug. 10 to win its fifth straight NL East championship.

So now, Showalter must quickly get his team refocused for a playoff run after the disappointment of leading the division for all but six days this season and still coming up short of a first-round bye.

Meticulous by nature with a never-ending thirst for information, Showalter ranks 19th in career wins with 1,652 over 21 seasons on the bench with five teams, including Texas. He became the first Mets manager to win 100 games in his debut with the club.

“He had a long layoff, so he probably thought a lot about if he came back, what he was going to change," reliever Adam Ottavino said. "Seems to me like he’s keeping it pretty simple, and that works well when you have an older group or a good group.”

Perched on the dugout railing, jotting down thoughts in his little black notebook while players reach for tablets nearby to scroll through game video, Showalter has brought a steady hand and wealth of experience to the Mets, helping to instill maturity and professionalism on a team that never lost more than three in a row this year.

“It’s still about relationships,” he said. “It’s about the players. It’s always about the players, and trying to bring what they need. And every situation’s different. You don’t ask them to adjust to you, you adjust to what their needs are. That’s always been the same.”

Off the field, Showalter likes to crack jokes with reporters and enjoys examining the nuances of baseball, whether it be an obscure rule or the proper way for a right-handed first baseman to guard the line late in a game.

Ask him a question, he might expound on something completely off topic that was weighing on his mind.

What makes him uncomfortable, though? Talking about his own success and quest for a championship.

“I think he’s content, whether we win it, lose it (or if) he ever gets it," Ottavino said. "But I think at the same time, if he does get it, I think you’ll find out then what it meant to him.”