The World Series contenders have been whittled from a dozen to just eight teams. And after what seems like an eternity, the big boys are taking to the postseason stage and encountering the underdogs that remain.

Both the American and National League Division Series feature squads that look very complete, from top to bottom, starter to reliever, along with a handful of ad hoc upstarts that nonetheless carry the vibes of dangerous October teams.

As the Division Series get ready to roll, USA TODAY Sports zeroes in on the four players most pivotal to their series’ outcome:

Phillies vs. Mets: Zack Wheeler, Philadelphia

Not often that the most important guy will throw the very first pitch of the series, but here we are. The Phillies flirted with baseball’s best record all year but plunged into a few valleys in the second half. Their star-studded lineup can go off at any time – yet runs the risk that any team encounters when they’re jammed into a short series after a layoff.

Follow every MLB game: Latest MLB scores, stats, schedules and standings.

And the Mets are floating into Citizens Bank Park on the wings of Pete Alonso’s miracle home run in Game 3 of the wild card series at Milwaukee, capping a roughly 100-game stretch where the vibes are immaculate. The final leg of the journey: Four games in three days, first just to get in and then to survive the first round.

It’s Wheeler’s job to ensure their adrenaline finally runs out.

With No. 3 starter Ranger Suarez pushed toward the back of the rotation for health and performance reasons, and No. 2 starter Aaron Nola pushed to Game 3 so Cristopher Sanchez can pitch at home, the Phillies are ever-so-slightly out of sorts, especially for a team that won 95 games. Wheeler is the closest thing Philly has to a sure thing.

He posted a 1.89 ERA in his last 11 starts, giving up two runs or less in all of them. Best he does even better in Game 1, lest the Mets believe they’ve gotten hot again.

Dodgers vs. Padres: Teoscar Hernández, LA

So many superstars and as many curiosities in the Dodgers lineup.

How will Shohei Ohtani do in his first taste of the postseason? Can Mookie Betts erase the burn of an 0-for-11 performance in the ’23 ALDS? Can Freddie Freeman (1 for 10) do the same, while bouncing back from an ankle sprain?

There’s one All-Star hitter with little noise surrounding him, and that would be the affable Hernández, who slugged 37 home runs this year and racked up an .840 OPS. Sure, it’s a pretty sweet gig batting behind Ohtani and Betts and Freeman, but Hernández absolutely made the most of it.

In his last postseason series, Hernández had a two-homer game for Toronto, but is 1 for 14 otherwise in the playoffs. He’s also 1-for-11 lifetime against Padres ace Dylan Cease, who will start Game 1 and would also start a Game 5.

Small samples, all, but it’s that time of year again. The Dodgers enjoy home-field advantage in this series but lost their last three games of the 2022 NLDS, two of them at a raucous Petco Park. They’d be wise to hold serve at Dodger Stadium, particularly since the back end of their rotation is even more troubling than the front, and getting out of Petco with the season intact will be challenging.

 Hernández running into a few balls would take the pressure off a lot of people – particularly if they get on base ahead of him.

Yankees vs. Royals: Austin Wells, New York

Would you pitch to Aaron Judge in a closely contested playoff game?

Some have tried and lived to tell about it. The Houston Astros held Judge to one hit in 16 at-bats in the 2022 AL Championship Series – this just weeks after Judge set an AL record with 62 home runs. And Judge’s career playoff slash line – .211/.310/.462 – pales compared to his .288/.406/.604 mark.

But Judge was once again on another level this year - .322/.458/.701 and 58 homers will ship another AL MVP plaque to his home – and remains the best all-around hitter in the game. And heck, the man already has 13 postseason home runs in 171 at-bats – all without Juan Soto batting in front of him.

So we’ll see how aggressive the very good Kansas City Royals pitching staff is with the 6-7 Bronx behemoth. Yet it stands to reason that the Royals will ask the Yankees not named Juan or Aaron to beat them until they prove otherwise.

Enter Wells. Since Aug. 30, the rookie catcher was the Yankees’ most frequent cleanup hitter behind Judge, a span in which he batted .148 and struck out 21 times in 92 plate appearances.

Yet Wells doesn’t need to make the Royals pay – and he did hit 13 homers this year – every time they duck Judge. Putting up competitive plate appearances will go a way toward forcing the Royals to dip into their bullpen sooner than they’d like.

Hey, it’s going to be on a lot of guys – Giancarlo Stanton, Jazz Chisholm, perhaps Jasson Dominguez or Alex Verdugo – to make sure Judge isn’t spending more time removing elbow guards and jogging to first than he is rounding the bases.

But Wells is more often than not the first line of defense. And he at least needs to make the Royals think about him a little bit.

Guardians vs. Tigers: Beau Brieske, Detroit

Yeah, you knew we had to get weird for this series.

With just one dominant starting pitcher looming over this AL Central matchup – and Tigers lefty Tarik Skubal won’t pitch until Game 2 after dominating the Houston Astros in the wild-card series – the onus will fall on Cleveland manager Stephen Vogt and Detroit counterpart A.J. Hinch to deploy their excellent bullpens in optimal fashion.

And this is what makes Detroit very dangerous in this series: The Tigers have been living like this for two months. Perhaps that’s why they made a two-game sweep of the Astros look so easy: Save for an ill-advised appearance from prospect Jackson Jobe, Detroit’s bullpen covered 10 ⅓ innings in two games and gave up one run.

And Brieske might be their most important weapon. When closer Jason Foley struggled to close out Houston after Skubal’s six-inning gem, Brieske came in to absorb the final two outs. A day later, he was summoned with one out and one on in a scoreless game in the fifth inning.

Brieske recorded the next four outs, with one walk erased by a double play, as Detroit finally took the lead on a Parker Meadows home run.

It was kinda like that all September as Detroit went 17-8 to chase down a playoff spot. Brieske started five games and finished two others last month. He entered games in the first, sixth, seventh, eighth, ninth and 12th innings – and posted a 1.06 ERA in 17 innings.

So when you see Hinch summon Brieske against Cleveland, know that it just might be the most pivotal point in the game. And that Brieske will probably get the job done.