By MARK SIMON

Leading up to Opening Day, we’re going to preview all 30 MLB teams and how they could fare defensively in 2021.

A team’s hitting and pitching are easy to evaluate when previewing a season but defense is a little harder because of the nature of the numbers available to assess a player’s skill.

But that sort of thing is our specialty and we’re happy to take our best shot at it.

Today’s look is at the NL Central, which could have four of the best defensive teams in baseball this season.

Brewers

Greatest Strengths: The Center Field/Right Field combo; Second Base

Biggest Weaknesses: Left Field

The Brewers made a concerted effort this offseason to return to the look of their 2018 NL Central-winning team, which finished second in the majors in Defensive Runs Saved.

They added three-time reigning Fielding Bible Award winner Kolten Wong to play second base and Gold Glove-winning outfielder Jackie Bradley Jr. to team up with opt-out returnee Lorenzo Cain in some combo of center field and right field.

Milwaukee was a combined 13 runs below average at second base and those two outfield spots in 2020. If their players hold to form, they’ll be well above average there in 2021.

Some might be rankled by the designation of left field as the team’s biggest weakness, but Christian Yelich cost the Brewers six runs there last season. He may fare better working with Bradley and Cain.

The great unknowns are how Keston Hiura, who has never played first base professionally, handles the move there, and how Omar Narváez fares beind the plate. Hiura’s performance (or that of potential position partner Daniel Vogelbach) could swing the success of the Brewers’ defense.

Whether Narváez’s 2020 improvements in pitch framing hold could greatly impact Miwaukee’s pitching performance.

Cardinals

Greatest Strengths: Third Base, Being average or better elsewhere

Biggest Weaknesses: None of significance

The Cardinals are the best defensive team in MLB heading into 2021. They added perennial Gold Glove third baseman Nolan Arenado, which more than offsets the loss of second baseman Kolten Wong to the Brewers.

Wong will be replaced by Tommy Edman, who has shown himself to be capable of handling that position in a small sample (8 Runs Saved in just over 250 innings). The Cardinals are above-average at first base (Paul Goldschmidt), shortstop (Paul DeJong), and likely all three outfield spots (2020 Fielding Bible Award winner Tyler O’Neill in left field, Harrison Bader, and Dylan Carlson). They even have a Fielding Bible Award candidate at pitcher in Miles Mikolas.

Amazingly, the Cardinals weakest link may be catcher, where Yadier Molina is 38 and not what he once was. Just don’t tell Molina or José Siri that. Molina’s skill at deterring the running game still holds true.

Cubs

Greatest Strengths: Shortstop, Right Field, First Base

Biggest Weaknesses: Third Base

For all the heat the Cubs took this offseason in shedding key components of their team, they still retain a very good defensive squad.

Javier Báez led the majors in Defensive Runs Saved two seasons ago in his first full year at shortstop and was solidly above-average in 2020. He’s way more than a guy with a reputation for making flashy tags.

Jason Heyward is not the defensive superstar that he once was, but with 15 Runs Saved in right field in the last 3 seasons, he’s still likely to be pretty good, and he’s got a good outfielder Jake Marisnick backing him up. Anthony Rizzo too provides little to worry about at first base.

Second baseman Nico Hoerner is in a similar boat to Tommy Edman of the Cardinals. Both have good numbers in a small sample (in Hoerner’s case, 5 Runs Saved in just over 200 innings) and will be looking to prove their legitimacy over 162 games.

Third base is a concern given that Kris Bryant played less than half of the team’s games there last season and David Bote, who fared well there in 2018, posted -4 Runs Saved in 2020. But there isn’t anything else that should greatly worry this team on the defensive side.

Pirates

Greatest Strengths: Third Base, Second Base, Catcher, Left Field

Biggest Weaknesses: Shortstop

It is possible that the Pirates could be both one of the worst teams in MLB this season and one of the game’s best defensive teams.

Why do we say that?

The Pirates are solid in the four spots we listed as strengths. In his 24-game MLB cameo, Ke’Bryan Hayes more than lived up to his billing as a hitter and matched expectations that scouts gave in dubbing him one of the game’s top defensive prospects.

Second baseman Adam Frazier has totaled 17 Runs Saved at second base the last three seasons, good for sixth-most at the positon. Leftfielder Bryan Reynolds placed second in the Fielding Bible Awards voting last year. Catcher Jacob Stallings, who ranks second in Runs Saved at the position the last two seasons, placed third in Fielding Bible voting in 2020.

Positions of concern are shortstop, where Kevin Newman has cost the team 14 runs with his defense the last three seasons, and first base, where Colin Moran will replace Josh Bell. The Pirates will hope the move across the diamond helps. Moran cost the Pirates 18 runs at third base in 2019, though only 1 run in 22 games at first base in 2020.

Reds

Greatest Strengths: Catcher

Biggest Weaknesses: Right Field, Third Base

The NL Central features four of the top defensive teams in baseball … and the Reds, who might be one of the worst.

The Reds’ best defender is their starting catcher, Tucker Barnhart, who won his second NL Gold Glove last season and finished second in Fielding Bible Award voting to Roberto Pérez. Barnhart has turned his pitch-framing skill from a liability into a strength the last few seasons. And he’s been one of the game’s top pitch blockers for almost his entire career.

Beyond that, the Reds have question marks.

A notable one is whether first baseman Joey Votto is the guy who saved them 7 runs in 2019 or the one who cost them 7 in 2020. They also have a couple of liabilities in the field in right fielder Nick Castellanos (an MLB-worst -40 Runs Saved in right field since 2017) and third baseman Eugenio Suárez (-10 Runs Saved the last 2 seasons).

This is a team that doesn’t have defensive capability to match up with any of the others in the division.