In a National League Central that features four of the five clubs bunched pretty close together, the quality of the rotations could make the difference when the season reaches the stretch run.

Three teams -- Chicago, Cincinnati and Pittsburgh -- lost front-line starters from their 2020 seasons, and all five clubs in the division have at least one question mark as Spring Training rolls on. But from Jack Flaherty and Kyle Hendricks to Brandon Woodruff and Sonny Gray, there are still plenty of big names who should stand out in 2021.

As our position-by-position series continues, we’re taking a look at the NL Central rotations.

BREWERS

What’s known: The Brewers have a solid, home-grown 1-2 punch atop the rotation in Brandon Woodruff and Corbin Burnes, the former who was an All-Star in 2019 and possesses some of baseball’s best fastball metrics, and the latter who harnessed a plus-plus sinker-cutter combination in '20 and finished sixth in NL Cy Young Award balloting. Both pitchers are poster boys for having patience with developing pitchers, particularly Burnes, who had an 8.82 ERA in 49 innings in '19 and was so bad the Brewers shut him down and sent him to their pitching lab to get right. Now he and Woodruff are bona fide top-of-the-rotation starters.

What’s unknown: Do the Brewers have enough depth behind their top two to cover the return to a 162-game schedule? Veterans Brett Anderson and Josh Lindblom are back, as are still-developing righty Adrian Houser and lefty Eric Lauer coming off down seasons. Swing man Freddy Peralta will be counted on to cover a heavy innings load as both a starter and a reliever, and the Crew may use a multi-inning lefty from the bullpen to make some starts. Even more unknown is whether former Cy Young Award contender Jordan Zimmermann, a Wisconsin native, can contribute this year. He’s a non-roster invitee bidding for a job. The Brewers always use a long list of starters and they will need more than ever this year given the jump in innings.

-- Adam McCalvy

CUBS

The known: The Cubs have one of the game’s more reliable and predictable arms in right-hander Kyle Hendricks. He took the ball on Opening Day last season and spun a shutout after the quick Summer Camp ramp-up. Hendricks has been the picture of consistency with his precision-based approach, and he should give Chicago a sound tone-setter. Behind him, the Cubs have right-handers Jake Arrieta, Zach Davies, Trevor Williams, Adbert Alzolay and Alec Mills as the primary options for an overhauled staff that lost Yu Darvish, Jon Lester, José Quintana and Tyler Chatwood over the winter.

The unknown: Trading Darvish was a big risk for a Cubs team that still wants to contend in 2021. Now, Chicago is short one of the game’s elite arms, and it is counting on a staff that is reliant on soft contact. The Cubs’ staff is not built to miss bats, with the exception of Alzolay, who will surely face innings limitations given his lack of MLB experience. Arrieta and Williams are both attempting comebacks, along with righty Shelby Miller (signed for depth on a Minor League deal). Defense will be critical for this Cubs’ staff, and that slim margin for error could be exposed over a full season.

-- Jordan Bastian

CARDINALS

The known: The Cardinals’ rotation has the chance to be among the best in the NL -- with no shortage of known entities. Jack Flaherty is the ace, fully entrusted even after his lackluster 2020. It’s well known what Adam Wainwright brings to the table, entering 16th season and off a stellar 2020. Miles Mikolas and Kwang Hyun Kim have proven track records, with the latter bursting onto the scene with a 1.62 debut ERA last season. Of all the NL Central rotations, the Cards’ may have the highest floor.

The unknown: But with a high floor, how low does that make the ceiling? If the Cardinals’ rotation candidates (their No. 5 starter is to be determined) hit their desired marks, it’ll be smooth sailing. But can Flaherty be the ace he was before 2020? Will Wainwright be durable, set to turn 40 in August? Is Mikolas, who was scratched from a sim game Monday, going to be fully healthy returning from forearm surgery? Has Kim been “figured out” now ahead of his second MLB go-around? And who takes the fifth spot? Carlos Martínez, Alex Reyes and John Gant are options, but each holds their own bevy of questions.

-- Zachary Silver

PIRATES

The known: Steven Brault, Mitch Keller, Chad Kuhl and Tyler Anderson are expected to get the bulk of the starts for the Pirates this season. JT Brubaker, Cody Ponce, Wil Crowe and Miguel Yajure will also compete for a spot, though the Pirates may also use them as bulk relievers as they try to piece together enough innings to cover 162 games. The Pirates could acquire one more free-agent arm for depth, or they could rely on pitchers at Triple-A like James Marvel, Chase De Jong and others.

The unknown: How many starts will the starters make? Manager Derek Shelton said he’d be “shocked” if guys were making 30 starts this season, coming off a shortened 60-game season. The lost year of prospect development also puts into question whether a prospect like Cody Bolton will get a shot to make their debut in 2021, or whether the organization sees the development time as a premium and will be more cautious with callups. Come September, it may be more beneficial to use them and ramp down the more everyday arms.

-- Jake Crouse

REDS

The known: Even with the free-agent losses of Trevor Bauer and Anthony DeSclafani, the top of Cincinnati’s rotation is sound with Sonny Gray and Luis Castillo forming a solid 1-2 punch. Known for a filthy curveball, Gray is 16-11 with a 3.07 ERA over 42 starts in two seasons with the Reds. Castillo owns one of the nastier changeups in the game, Castillo overcame a subpar first month of last season to go 4-1 with a 2.20 ERA in his final five starts. The third start will be taken by Tyler Mahle, who stepped up amid injuries and posted a 3.59 ERA in 10 games (nine starts).

The unknown: There is less stability in the fourth and fifth spots. The likely No. 4 starter is left-hander Wade Miley, who was 0-3 with a 5.65 ERA in six games (four starts) amid injuries and poor performances. The club is using camp to audition candidates for the fifth spot with Michael Lorenzen, Tejay Antone, Jeff Hoffman and José De León. Lorenzen offers an added dimension because he can pinch-hit, pinch-run and play the outfield on days he doesn’t pitch, and he wouldn’t always need to be lifted for a pinch-hitter on days he was on the mound.

-- Mark Sheldon