Who, or what, will make the difference the rest of the way for the teams with the most at stake?

On Friday, we looked at the biggest concern facing each of the 12 teams in playoff position. Today, we continue to assess the current MLB postseason field, as our writers weigh in on a key X-factor for each of those teams over the final three weeks and into October.

National League

Jacob Misiorowski allowed one run in seven innings against the Pirates on Sunday. (Justin Berl / Getty Images)Brewers: Jacob Misiorowski 

It will be fascinating to see how the Brewers utilize rookie Jacob Misiorowski this October. He burst onto the scene this summer and made the All-Star team after five career starts. The next act was a lot less riveting. In his first six starts after the Midsummer Classic, Misiorowski posted a 6.45 ERA and completed five innings just once.

His stuff remains eye-popping. The Miz throws a fastball that averages 99 mph and a slider that sits at 94 mph. When he can harness those pitches for strikes, he can be devastating. If he’s right, he can slot into the Brewers’ rotation behind Freddy Peralta and Brandon Woodruff, offering a higher ceiling than fellow starters Quinn Priester and Jose Quintana. Or the team can attempt to use him to lengthen its bullpen, a role in which he excelled at Triple A last year.

He can be a real weapon. The Brewers just need to figure out how to best deploy him. — Andy McCullough

Phillies: Bryce Harper

It’s too easy to focus on Bryce Harper because he’s Bryce Harper, but the Phillies’ star is having a pedestrian season by his standards. He is carrying the lowest OPS he’s had since 2016. All of the underlying metrics look fine; he’s striking out at a rate lower than his career mark and hitting the ball as hard (on average) as usual.

But, since joining the Phillies, Harper has often saved his best for September. He’s hit .265/.386/.516 in his first six Septembers with the Phillies — and that includes 2022, when Harper hit .196 as he tried to regain his timing from injury. (That didn’t affect him come October.)

Maybe it’s harder for Harper to find motivation during the 162-game grind the older he gets, but he often rises to the moment. He can power the Phillies to a first-round bye with a strong September. — Matt Gelb

Dodgers: The rotation 

If — and it’s a major if — the Dodgers’ rotation can get through the season’s final month unscathed, they might be the best unit in the sport.

Shohei Ohtani still has ace-caliber stuff. Yoshinobu Yamamoto will receive Cy Young Award votes. Blake Snell has shown he’s still one of the most unhittable pitchers in baseball. Tyler Glasnow has shown unhittable flashes. Clayton Kershaw has turned back the clock. Even Emmet Sheehan would be an intriguing postseason starter most years. More than one of these names won’t make starts this October, which goes to show the depth the Dodgers boast. — Fabian Ardaya

Cubs: Michael Soroka 

He won’t be the starter the Cubs hoped they were getting at the trade deadline, but as Michael Soroka rehabs, it sounds like his velocity is back and he could help the team out of the bullpen down the stretch. His numbers in that role last season were impressive, and if he can come close to matching them, he could help the team win and give time off to key relievers like Brad Keller and Andrew Kittredge as the Cubs try to stay fresh and healthy heading into the postseason. — Sahadev Sharma

Padres: Fernando Tatis Jr.

For all the concern about their starting pitching, the Padres won’t go far without more slug from a less-than-intimidating offense. Tatis has been the chief culprit behind the lack of pop; after swatting 13 home runs by late May, he went deep just five times over the next three months.

Still, Tatis has shown the ability to power back up on short notice. He hit seven home runs last September while playing with a stress reaction in his right leg, and he hit four more in the Padres’ first five games of the 2024 postseason. Now, San Diego desperately needs a similar resurgence. Tatis is a supreme defender in right field, but with center fielder Jackson Merrill still in the throes of a sophomore slump, Tatis’ offensive form — or lack thereof — will largely determine the team’s trajectory.  — Dennis Lin

Mets: Nolan McLean

Mets pitcher Nolan McLean looks like a Game 1 starter. The thing is, he has thrown just four major-league starts. Still, he has looked excellent in each outing (1.47 ERA, 0.759 WHIP in 26 1/3 innings). More to the point, he has pitched like someone who has done this before. If McLean remains this good, it wouldn’t be surprising to see the Mets give him the ball to start a playoff series. They also may have to.  — Will Sammon

American League

Vladimir Guerrero Jr. has hit .517/.576/.828 over his last seven games. (Jim McIsaac / Getty Images)Blue Jays: Vladimir Guerrero Jr.

George Springer will get MVP votes. Jeff Hoffman has been both a carrying force and anxiety inducer at times this year. Bo Bichette leads the majors in hits. But the Blue Jays didn’t give any of them $500 million this spring. Vladimir Guerrero Jr. is the face of Toronto’s franchise for a reason. At his best, he’s one of the three best hitters in MLB.

Peak Guerrero flashed in July, as he hit .333 with more walks than strikeouts. But a hamstring injury paused the first baseman’s second-half hot streak. The Jays’ offence is deep and dynamic, able to thrive despite merely good play from Guerrero. But if he can regain his elite form, Guerrero can carry the Jays to their first division title in a decade. — Mitch Bannon 

Tigers: Parker Meadows

Paul Sewald and a bundle of other relief pitchers could qualify. But let’s go with Parker Meadows. The outfielder who played elite defense and had an .840 OPS in the final two months of last season has been banged up nearly all year. And when he has been healthy, he hasn’t been the same. He hit .200 in 125 at-bats and graded out at minus-2 Defensive Runs Saved before going on the injured list with a quad strain in late July.

Meadows returned from the IL on Friday, homering in a loss to the White Sox. If the Tigers could get anything close to the best version of him the rest of the way, it changes the complexion of their team. — Cody Stavenhagen

Astros: Cristian Javier 

Three years ago, Cristian Javier started the second no-hitter in World Series history, finishing a fabulous season that he parlayed into a $64 million contract extension. Javier’s performance dipped in 2023 and Tommy John surgery sidelined him for most of 2024. He has a 1.328 WHIP and 4.43 ERA across his first five starts back. Getting anything close to Javier’s 2022 form will make Houston’s rotation far more formidable behind Hunter Brown and Framber Valdez. — Chandler Rome

Yankees: Aaron Judge 

This time, there will be no Juan Soto, and Giancarlo Stanton can’t do it all by himself. The Yankees need Aaron Judge to put up Aaron Judge numbers in the postseason. They need him to author major moments and to be the catalyst that he largely hasn’t been throughout his postseason career.

In 58 career postseason games, he’s hit just .205 with a .836 OPS — well shy of his lifetime regular season mark of 1.021. Last postseason wasn’t any better as he hit .184 with three homers and a .752 OPS over 14 games. In his first trip to the World Series, he went 4-for-18 (.222) with one home run.

Then there’s the matter of his defense. After 27 straight games as a DH, Judge returned to right field on Friday — and failed his first test. The Yankees say they expect he’ll be in the outfield and mostly healed from his right flexor strain by October, but it’s still a question mark. — Brendan Kuty 

Red Sox: Offensive streakiness

The Red Sox lost rookie Roman Anthony for likely the remainder of the regular season last week. It’s a big blow to the lineup, and replacing his .917 OPS since the All-Star break won’t be easy. The Red Sox are still without Wilyer Abreu, who is second on the club with 22 homers, as he works his way back from a calf strain.

They have been one of baseball’s better offensive teams, ranking in the top 10 in average and OPS. But they’ve also had prolonged stretches of streakiness at the plate. Avoiding those slumps could be their biggest X-factor as they try to reach the postseason. — Jen McCaffrey

Mariners: Cal Raleigh

There’s a reason it’s so hard to be a top run producer as a catcher. The position is extremely demanding, and playing it as often as Cal Raleigh does is bound to take a toll. It’s been a special year for Raleigh, the first primary catcher ever to hit 50 homers in a season. But he entered the weekend at .206/.296/.461 since the All-Star break.

It helps that the Mariners have a deeper lineup than they did in the first half, when Raleigh carried them. But they need more from a player who has already given so much — and if Raleigh can rediscover his first-half form (.259/.376/.634), the Mariners have a better chance of outslugging some of their pitching problems. — Tyler Kepner

(Top photo of Nolan McLean: Jim McIsaac / Getty Images)