The story below is a collaboration between writers from MLB.com and Yahoo Sports, who are joining forces this season to cover topics from around baseball.

Which players are the X-factors of the second half?

With the All-Star break behind us and the playoff chases getting ready to heat up, we put that question to six writers (three from MLB.com and three from Yahoo Sports). Their task was to identify players with an opportunity to put their stamp on the final two-plus months of the 2024 season — not only by playing well but by helping to push their clubs into a postseason berth or a division title … or perhaps beyond.

Here are six players who could make the biggest impact with their stretch-run performance. (All stats below are through Monday’s games.)

• Click here to sign up for the Yahoo Sports AM daily newsletter.

Julio Rodríguez, CF, Mariners

The Mariners had a 10-game lead in the AL West entering play on June 19, but they’re now locked in a neck-and-neck battle with the Astros, who are looking to take the division crown for the seventh time in the past eight seasons. With one of the lowest-scoring offenses in the game, the M’s are in desperate need of a bat and may very well add one at the Trade Deadline. That said, getting a big finish out of J-Rod once he returns from a right ankle sprain could be just as impactful as any trade.

Rodríguez went into the All-Star break with just 10 homers and a .690 OPS over 97 games, but we know how good he can be when he’s right. The youngster was one of the best players in baseball a year ago, placing fourth in the AL MVP Award voting after producing 32 homers, 37 steals and an .818 OPS in his age-22 season. He was starting to return to form before his injury, slashing .439/.500/.805 with four homers in 13 games from July 3-20. A rejuvenated Rodríguez could give Seattle the offensive boost it needs to win its first AL West title since 2001, assuming he doesn’t have an extended stay on the injured list.

— Thomas Harrigan (MLB.com)

Garrett Crochet, LHP, White Sox

This is assuming, of course, that the White Sox, with MLB’s worst record, opt to trade Crochet, who is not a free agent until after 2026. Given the state of their organization, it’s fair to assume the Sox won’t compete within that window. That makes a trade of the 25-year-old All-Star lefty a relatively likely proposition at the upcoming Deadline. And while there are concerns about Crochet’s workload — he has already doubled his previous career high in innings — he’s an impact, game-changing arm no matter how he’s deployed.

Entering Tuesday’s start against the Rangers, Crochet had tossed 107 1/3 innings with an ERA of 3.02 so far in this breakout season. His under-the-hood, predictive stats are even more favorable. This is, right now, one of the most unhittable hurlers in the league. Whichever team lands the gas-chucking southpaw will immediately add the league leader in strikeouts, somebody who would start Game 1 of a playoff series for a number of contending teams. That’s what I call an X-factor.

— Jake Mintz (Yahoo Sports)

Royce Lewis, 3B, Twins

When Lewis is healthy, he’s one of the best baseball players on the planet. Through his first 94 career games, Lewis has bopped 27 home runs, slashed .303/.361/.584 and posted a 158 OPS+ that trails only Aaron Judge, Yordan Alvarez, Shohei Ohtani and Juan Soto (min. 350 plate appearances) since his debut season in 2022.

Staying healthy is the caveat, though. Lewis tore the ACL in his right knee 12 games into his MLB career — the second time he’d done that in pro ball — and has dealt with various ailments since returning to the Majors last May. Lewis is currently on the injured list with a right adductor strain but is expected to return before the end of the month.

If Lewis can stay healthy the rest of the year, it bodes well for a Twins team that only has a small cushion in the AL Wild Card race. It’s also not inconceivable that a healthy Lewis could spark a Twins run to a division title, as they already have gained significant ground on the first-place Guardians, going from nine back on June 25 to just four back entering Tuesday.

— Brent Maguire (MLB.com)

Tyler Glasnow, RHP, Dodgers

There might not be a playoff contender with bigger questions in the starting rotation than the Dodgers. And that makes Glasnow as valuable as any starter in baseball. Prior to his recent bout of lower back tightness that landed him on the IL, Glasnow had been everything the Dodgers hoped he would be in his first season in L.A., dominating at the top of the rotation.

The problem is that what’s behind him has been very murky. While Gavin Stone has been electric, he and Glasnow are the only real certainties for the Dodgers at this point. It’s unclear if or when Yoshinobu Yamamoto will return, and with Bobby Miller sent to Triple-A and Clayton Kershaw just now set for his season debut after rehabbing from shoulder surgery, this is far from a complete rotation.

Glasnow will return from the IL on Wednesday against the Giants, and his ability to stay healthy in the second half will be imperative if the Dodgers hope to be the team we expect them to be come October.

— Russ Dorsey (Yahoo Sports)

Kodai Senga, RHP, Mets

The Mets have been waiting for Senga all season, and he’s finally here, just in time for their playoff push. (The right-hander could make his 2024 debut as soon as Friday.) They somehow managed to streak into playoff position to end the first half without Senga. They’ve already gotten bumps from Grimace and Jose Iglasias. If anything can spark them to a postseason berth now, it’s getting their ace back for the stretch run.

Remember that Senga is a Cy Young-caliber arm. Remember that the “ghost fork” is one of baseball’s most unhittable pitches. Remember that Senga went 12-7 with a 2.98 ERA and 208 strikeouts in his first season facing Major League hitters — and ended the season on a run of 14 starts over the final three months where he went 6-2 with a 2.44 ERA, 101 K’s and a 10.7 K/9 rate. For the Mets, this is the classic ” the biggest addition comes from within” situation. Considering the logjam in the National League Wild Card race, Senga is the type of player who could make the difference in the Mets making the playoffs or missing them.

— David Adler (MLB.com)

Manny Machado, 3B, Padres

It was just two years ago that Machado finished second in NL MVP voting and helped power the Padres to within a couple of wins of the World Series. Since then, though, he has played through several injuries that have diminished his overall production from elite to merely very good, with only occasional flashes of the MVP candidate version of Machado appearing along the way.

Now in the thick of the NL Wild Card picture, the Padres have thus far been fueled by their surprisingly excellent outfield, thanks to the resurgence of Fernando Tatis Jr., the immediate success of 21-year-old rookie Jackson Merrill and the stunning breakout of veteran Jurickson Profar. The infield, meanwhile, has been less promising, with Xander Bogaerts also hampered significantly by injuries and Ha-Seong Kim not quite as productive at the plate as he was a year ago.

Machado, meanwhile, has started to look more like himself recently, opening the door for what could be a crucial final few months for the veteran third baseman if San Diego wants to return to October. In 25 games since his OPS fell to .662 on June 18, Machado has hit .293/.336/.535 with seven home runs, far more reflective of the kind of hitter we saw from 2020-22. Machado sustaining this excellent form down the stretch would go a long way toward solidifying San Diego’s status in the NL postseason race.

— Jordan Shusterman (Yahoo Sports)