Baseball in the 21st century isn’t as complicated as folks make it out to be.

One example: if a team’s bullpen spells r-e-l-i-e-f better than almost everyone else’s relievers do, then maintaining sanity throughout baseball’s absurdly long season becomes infinitely more doable.

A dazzling relief corps confers a wealth of advantages in a sport that, every year, becomes more specialized

A volatile bullpen, conversely, destabilizes the journey while also making the manager look like a dummy.

See Craig Stammen and Tony Vitello, who chatted on the field Thursday before their teams opened a four-game series in the East Village.

Linked by their status as rookie managers in the National League West, Stammen and Vitello inherited bullpens of vastly different aptitude.

Predictably, Stammen’s team has fared better.

Padres relievers have led San Diego into strong contention for a wild-card playoff spot. More than anyone else, they’ve created the likelihood that A.J. Preller will trade for big leaguers ahead of the trade deadline Monday afternoon.

Giants relievers, meantime, have spelled g-r-i-e-f.

Compared with a Padres crew that stood first in win shares, third in innings pitched, fifth in ERA and sixth in fielding-independent ERA heading into Saturday’s game. The Giants sat 25th, 26th, 19th and 20th in those categories.

So Giants general manager Buster Posey will be looking to sell off big leaguers, such as second baseman Luis Arraez, the ex-Padre figures to attract offers from the Rays and other contenders.

As a former reliever, Stammen may have been better equipped than Vitello in the care and feeding of a relief corps.

Choosing well, it appears, after Preller hired him, Stammen retained longtime bullpen coach Ben Fritz and pitching coach Ruben Niebla, whose time together has seen the Padres earn three wild-card berths.

Let’s not complicate this: a bullpen backstopped by Mason Miller and Adrián Morejón will shorten the game for any team, even if the manager is Morris Buttermaker.

Getting a lot of good work from several other relievers as well, Stammen’s bullpen has bought time this year for a Padres offense that sits next to last in runs scored in the National League, even with the recent turnaround that Manny Machado predicted.

As for the Padres’ starting pitchers, they ought to buy Rolex watches for a bullpen that’s helped fortify a unit that in July threatened to capsize the season.

Stammen used one word to describe the bullpen’s season to date.

“Amazing,” he said Saturday.

Stammen mentioned setup man Jason Adam, who is expected back about four weeks, as well as Jeremiah Estrada and Bradgley Rodríguez in addition to Miller and Morejón.

“Those are like six closer-type guys I just named, and they’re all in our bullpen,” he said.

“Then, that’s not even saying Wandy Peralta, Yuki Matsui, Kyle Hart, David Morgan — the list goes on and on,” he said.

“Now,” added the manager, perhaps feeling a tad froggy, “you can add (No. 5 starters) Germán Márquez, Griffin Canning, JP Sears and Randy Vásquez to the group. Whoever we have down there, they’ve been willing to take the ball whenever, and they’ve all done a great job.”

The Giants occupy the other end of the spectrum.

Do they have a closer? No. A setup man who can rival Morejón? No.

In part because Posey failed him, Vitello shouldn’t be blamed for a Giants season that has devolved into an ugly soap opera.

But the drop-off from Bruce Bochy still appears steep for the Giants, who lost their way long ago.

Since Bochy was nudged aside despite having led the Giants to three World Series titles, San Francisco has gone new school (Gabe Kapler), old school (Bob Melvin) and new school again with Vitello, whom Posey hired away from the University of Tennessee (even though Vitello had never worked in professional baseball).

Not one of them has worked out. As we recall Melvin opting not to summon a white-hot Josh Hader to face fellow lefty Bryce Harper in Game 5 of the 2022 NLCS, precisely the kind of moment that put Hader on the team, know this too: Neither has any of those three managers recalled Bochy’s feel for managing a pitching staff and a bullpen. Those traits led the Giants’ Brian Sabean and Pat Dobson to pursue and hire Bochy two decades ago, after Padres CEO Sandy Alderson opened the door for his exit.

While the three World Series trophies the Giants display also must be noted, the Preller-Stammen tandem profiles as a Padres advantage over the Giants in a critical realm: relief.