We love baseball’s postseason, in part, because we do not know where the heroes will come from.

Remember Charlie Morton?

You probably know him as this season’s ace of the Rays’ pitching staff. Two years ago, he was a lot less well known.

That is, until he took the baseball in the sixth inning of Game 7 of the 2017 World Series.

The Astros led 5-0 at the time and needed four pitchers to get through the first five innings. Morton turned in one of the great relief performances in World Series history, pitching the final four innings and retiring the final 11 Dodgers in order in a 5-1 victory.

This was the guy who’d wondered if he’d land a Major League contact when he became a free agent after the 2016 season, and here he was a World Series hero. When he finished the eighth inning, Morton stepped into the visitors’ dugout at Dodger Stadium and went to fist bump Astros manager AJ Hinch.

Hinch told Morton he wasn’t done. Wait, what?

“You sure?” he asked.

The Red Sox got similar performances from Nathan Eovaldi and Steve Pearce in the 2018 World Series. And again, this is one of the best parts of the postseason. Next man up morphs into next hero up. With a tip of the hat to Morton, Pearce and Eovaldi, let’s take a guess at the 2019 X-factors for the 10 playoff teams. Some are big names, some are relatively unknown … but you’ll hear a lot about them the next few weeks.

A’s: Liam Hendriks, RHP
Hendriks was designated for assignment in 2018 and poured himself into a conditioning and nutrition program that jump-started his career. He may have saved the A’s season by assuming the closer’s role in late June and giving a struggling bullpen a reliable anchor. According to FanGraphs’ version of WAR, he was the most valuable reliever in the Majors this season (3.8 WAR).

Astros: Yordan Alvarez, DH
Alvarez’s arrival on June 9 transformed a solid offensive team into an extraordinary one. Before his debut, the Astros were averaging 5.12 runs per game with an .814 OPS. Afterward, they averaged 6.06 runs per game and an .870 OPS. Casual fans don’t know his name yet, but if the presumptive American League Rookie of the Year hits like he did this summer, the Astros’ offense will be unstoppable.

Braves: Mark Melancon, RHP
Melancon was acquired from the Giants at the Deadline, slid into the closer’s role in mid-August and has pitched some of his best baseball in years, converting all 11 save chances with a 2.60 ERA and 0.98 WHIP.

Brewers: Drew Pomeranz, LHP
Pomeranz has been reborn as a dominant late-inning reliever since the Brewers acquired him from the Giants at the Trade Deadline. His velocity has ticked up as he has embraced a completely different role and deepened a bullpen that was already one of baseball’s best.

Cardinals: Tommy Edman, UTIL
Fun fact: Among Cardinals with at least 300 plate appearances, Edman’s 120 OPS+ is the highest. With Matt Carpenter and Paul Goldschmidt having down years, Edman has been invaluable, starting games at third, second and right field since his Major League debut on June 9. He has been solid at all three positions, but it’s his offense -- .304/.350/.500 with 15 steals in 16 tries -- that has made him important to the Cardinals’ return to the postseason.

Dodgers: Cody Bellinger, CF
This could have been Hyun-Jin Ryu, Walker Buehler, Clayton Kershaw, Kenta Maeda or others. Teams that win 106 times can spread the credit to every corner of the clubhouse. Bellinger has taken the next step to being a great player, an impact performer in every way. He’s also the Dodgers’ best defensive player regardless of where he plays. But he wasn’t quite as dominant in the second half (.917 OPS) as he was in the first (1.124), and with Justin Turner still hobbled by an ankle injury that kept him out for much of September, the Dodgers need the best version of Bellinger to carry the offense.

Nationals: Howie Kendrick, UTIL
The Nationals were so deep in position players that they weren’t sure how much playing time Kendrick would get when he was re-signed. They wanted him anyway because of his leadership and the example he sets for young players. Turns out, he has been invaluable by starting at four spots and being one of the Nationals’ most consistent producers. His .344 batting average was the highest on the Nats (min. 300 PAs), and only Anthony Rendon had a higher OPS+.

Rays: Emilio Pagán, RHP
Pagan was an under-the-radar acquisition from the A’s as part of a three-team, seven-player trade with the Rangers last December. The Rays have helped him harness his 96-mph fastball and improve his slider to the point that he moved into the closer’s role in late July and is now part of what may be baseball’s best and deepest bullpen. He struck out 96 batters in 70 innings while issuing just 13 walks.

Twins: Luis Arraez, UTIL
The Twins made headlines this year by becoming the first team to hit 300 homers, and the pesky Arraez -- who hit .334/.399/.439 -- gives them a bit of balance. He doesn’t hit homers, but Arraez struck out in just 7.9 percent of his plate appearances, the lowest mark in the Majors for players with at least 350 plate appearances. The question now is health, as Arraez, 22, left Saturday’s game against the Royals with a sprained right ankle. If healthy, he seems likely to open the AL Division Series at second base, and Arraez also gives manager Rocco Baldelli flexibility since he can fill in at third and in the outfield while giving the Twins’ lineup a different look.

Yankees: Giancarlo Stanton, OF
Stanton is the ultimate X-factor in that he missed five months of the season and returned in time to play nine games in the final two weeks of the season, hitting .286/.382/.571, which looks a lot like his line in his 2017 National League Most Valuable Player season. Despite his injury woes, he is a player capable of putting a team on his back. This is the same guy who hit 30 homers in a 48-game stretch in ‘17, and he's on the perfect stage to show the world he can still be that guy.