The Post’s Mark W. Sanchez previews the NL West

O/U wins: 97.5

Key player: Mookie Betts. For the Dodgers to be historically great — which is a real possibility — they could use their $365 million man in peak form. The right fielder was merely very good (.854 OPS) but not great last season, and the lineup is even more ludicrous with the addition of Freddie Freeman.

Player who’ll need to step up: Andrew Heaney. The Yankees couldn’t fix him, and now the Dodgers will try while banking upon peripherals that signal he is better than his results have shown. He’ll slot behind Walker Buehler, Julio Urias, Clayton Kershaw and perhaps Tony Gonsolin in a stacked rotation.

Name you’ll get to know: Bobby Miller. The Dodgers both spend more and develop better than nearly every team, and their 2020 first-round pick is throwing triple-digit heat that pairs well with a nasty slider. If their rotation deals with injuries, they should have in-house solutions.

Biggest question mark: Trevor Bauer. There are all sorts of questions around Cody Bellinger, whose bat has disappeared since his 2019 MVP season, but there isn’t a greater unknown than the ace Los Angeles signed to a $102 million pact a year ago. The 2020 Cy Young winner is on administrative leave as MLB investigates sexual assault allegations. LA prosecutors decided against charging Bauer, who has two years and $64 million left on his contract.

How it’ll go down: There were predictions beginning last season that the Dodgers could be the strongest team in baseball history. This year, returning largely that same core, they have added Freeman and Craig Kimbrel. A 106-win team has gotten better and should leapfrog the Giants.

O/U wins: 85.5

Key player: Gabe Kapler. No team asked more from its manager last season, which turned Kapler into NL Manager of the Year. The Giants led the majors in pinch-hit at-bats, relying upon platoon advantages and employing essentially line shifts — one lineup against righties, one against lefties — to stun their way to the division title. Largely running back the same roster, can Kapler push all the right buttons again?

Player who’ll need to step up: Joey Bart. The largest hole is at the most critical position after seven-time All-Star Buster Posey surprisingly retired. Bart, the No. 2 overall pick in the 2018 draft who long has been viewed as Posey’s heir, has lost some of his prospect shine after a rough 2020 debut (41 strikeouts in 103 at-bats).

Name you’ll get to know: Sean Hjelle. There is no one bigger for the Giants, and we mean that literally. When the starting prospect debuts, he will tie Jon Rauch at 6-foot-11 as the tallest player in major league history. Hjelle, a string bean, rose to Triple-A last season.

Biggest question mark: Starting pitching health. Behind Logan Webb is a series of high-upside, significant-risk starters. Carlos Rodon is the new No. 2 after a big-time fade in last year’s second half. Behind the duo are Anthony DeSclafani, who was great against everyone except the Dodgers last season, and Alex Wood and Alex Cobb, who have lengthy injury histories.

How it’ll go down: Can they do it again? A season after a franchise-record 107 wins — and they needed every one — can the mixing and matching continue to match one of the most talented teams in baseball history? Probably not, but don’t tell that to Brandon Crawford & Co.

O/U wins: 90.5

Key player: Manny Machado. Without Fernando Tatis Jr. for possibly the next three months after wrist surgery, San Diego could use more offense from his left-side-of-the-infield mate. Machado might not be the face of the team, but he has been steady and excellent in three seasons since signing.

Player who’ll need to step up: Blake Snell and the aces who have not looked like aces. Snell, now four years removed from his AL Cy Young and entering the second season with the Padres, was ordinary last year. Chris Paddack was worse than ordinary, Yu Darvish faded down the stretch and injuries limited Dinelson Lamet to nine starts and Mike Clevinger, who had Tommy John surgery, to zero. Sean Manaea will help, but will any fallen star join Joe Musgrove atop the rotation?

Name you’ll get to know: CJ Abrams. The injury to Tatis may open the door for at-bats from the 21-year-old, the Padres’ top prospect and one of the best in the game.

Biggest question mark: Along with the boom-or-bust rotation, can San Diego get more out of contractual weights in Eric Hosmer and Wil Myers? Both are coming off down seasons and may be running out of time if San Diego can find the right trade partner.

How it’ll go down: Bob Melvin is tasked with doing what Jayce Tingler could not: maximizing the talent. There are still depth issues, though, that could keep them from hanging with the cream of the division.

O/U wins: 68.5

Key player: Kris Bryant. The Rockies traded Nolan Arenado and let Trevor Story walk only to throw $182 million at Bryant, who immediately became the face of the team. The 2016 MVP would need to have a throwback season while playing left field and get plenty of help for Colorado to be competitive.

Player who’ll need to step up: Antonio Senzatela. The pitching- and air-thin Rockies have few sure-things in the rotation behind German Marquez. Senzatela, a control artist on a new $50.5 million deal, had a great 2020 (3.44 ERA) but took a step back last season. The Rockies would love for him to become a legitimate No. 2.

Name you’ll get to know: Elehuris Montero. A big part of the Arenado trade, the 23-year-old corner-infield prospect knocked 28 homers between Double- and Triple-A last season and should debut this year.

Biggest question mark: There are plenty, but it’s the same concern always found in Colorado. The Rockies had the sixth-worst ERA in baseball last season and lost reliable starter Jon Gray this offseason. Who will record outs?

How it’ll go down: A lineup with Bryant, Charlie Blackmon, Ryan McMahon, C.J. Cron, Brendan Rodgers and Randal Grichuk could compete in some divisions. But not this one, and it will be another long season for a team that has finished fourth three years straight.

O/U wins: 66.5

Key player: Daulton Varsho. There isn’t another player in baseball asked to both catch and man center field. The athletic 25-year-old is the face of new-age flexibility — at premium positions — and posted a .290/.349/.530 slash line after the All-Star break last season, swinging his way to the top of the lineup.

Player who’ll need to step up: Madison Bumgarner. There are scenarios in which one of baseball’s worst staffs bounces back this season — there is hope with Zac Gallen and Merrill Kelly — but Arizona needs more from the big lefty, who’s been a bust in two seasons away from San Francisco.

Name you’ll get to know: Alek Thomas already has been to two All-Star Futures Games and this season should make his major league debut. The smooth-swinging outfielder hit .313 with 18 homers in Double- and Triple-A last season.

Biggest question mark: Arizona posted the second-worst staff ERA in baseball last season, with the bullpen a particular anchor. Adding ex-Yankees Mark Melancon and Ian Kennedy was not nearly enough help.

How it’ll go down: The Diamondbacks lost 110 games last season. They could enjoy a far superior year in 2022 and still rack up 100 defeats. They did nothing this offseason to promise a turnaround would happen quickly.