With roughly four weeks of MLB regular-season play remaining, playoff talk is heating up and the pretenders are finally beginning to distance themselves from the contenders. We’re also seeing a few underrated players stepping up for their respective teams, who will need contributions from these “x-factors,” especially in October.

These eight players will likely play an integral role in determining their club’s postseason fate.

8. J.D. Martinez

Many key performers in September are those that were absent for portions of the previous five months. Despite part-time service, Martinez drilled his 20th home run in Sunday afternoon’s 6-5 victory over Kansas City — the Tigers’ fifth win in the last six games. Detroit’s success will likely be predicated on how its offense performs, and there probably isn’t a more crucial piece than J.D. — who has the ability to hit for both power and average (.321 through 368 at-bats).

7. Jay Bruce

Acquired at the trade deadline from Cincinnati, Bruce’s arrival to the Mets came with the expectation of maintaining his run-producing ability at the plate. But two home runs, six RBIs, and a .183 batting average during August was vivid proof that the transition has been anything but smooth. Over the first four days of September, however, he went 5-for-12 with a pair of long balls — including one during the series finale versus Washington. Bruce bolstering the middle of the order as hoped can ease the pain of an injury-riddled roster and add to the Mets’ momentum being generated.

6. Yoan Moncada

It only took 187 minor league games before the Red Sox decided to give the Cuban third baseman a promotion. For a team loaded with offense, Moncada (age 21) will have the luxury of getting acclimated to MLB without the pressure of trying to be a savior. Based on his recent past, he can only add to Boston’s high-scoring attack. His first start came Sunday in Oakland, and he promptly delivered a run-scoring double for his first career hit and RBI. It was a good day also for the Sox, as they trounced the A’s, 16-2.

5. Aaron Sanchez

As mentioned in spring training predictions at hityah.com, Aaron Sanchez emerged as the ace of a Toronto staff that has the best ERA in the AL. The 24-year-old won 11 of his first 12 starts and posted a 1.59 ERA during the month of July. But as his innings accumulated, team management became more cautious. Following his August 20 outing against Cleveland, Sanchez was sent to the minors (Single-A, if you can believe it) to conserve his workload — only to return back to the big league club soon after and allow just one unearned run in six innings versus Baltimore on August 31.

4. Hunter Pence

He doesn’t do anything conventional. And should the Giants hold on and reach the playoffs again, they would have taken a path there that was just as confounding. Right now, it’s a tenuous situation at best. San Francisco, after holding the league’s best record at the All-Star break, is an MLB-worst 16-31 in the second half. For part of that time, the Giants were without several key pieces — Pence included. Now relatively healthy (and hitting two homers during the series at Wrigley Field), he’ll have a month to help right a ship on the verge of sinking.

3. Alex Gordon

The charge of the Kansas City Royals from mediocrity into playoff contention coincided with Gordon’s 2016 revival. As the defending World Champions rattled off 20 victories (to only nine losses) in August, Gordon led in homers (seven) and runs scored (21) to follow a July spent mainly recovering from injury. At four games out of a Wild Card, it remains a tough hill to climb. But if anyone can overcome this, it’s Gordon and these Royals.

2. Chris Tillman

In a tight AL East race, one player can make a difference. For a Baltimore club which relies mostly on the long ball, a good starting pitcher can make a world of difference. The Orioles’ record when Tillman starts is 20-6. With anyone else, they are 55-56. A late August shoulder injury provided reason to worry. Right now, as the team sits well within range of the division and clinging to the second AL Wild Card, Tillman is confident he’ll return to the mound by this weekend. If he can’t, the O’s playoff chances might be doomed.

1. Yoenis Cespedes

There is no denying the fact that no player meant more to his team’s late-season resurgence in 2015 than Cespedes, who made the most of his three months in Queens and helped lead the Mets to an NL East title and an NL pennant. This year, a repeat of the divisional crown is just about out of reach, but the playoffs are not. New York has won nine of its last twelve to put some serious heat on the Cardinals (who currently own the two NL Wild Card spot). The Mets schedule over the final four weeks are chock full of games against the Reds, Braves, Twins and Phillies. Seems like a perfect spot for Cespedes to get hot again.