Jim Leyland liked to say that momentum in baseball is only as good as the next day’s starting pitcher. He also won three consecutive American League Central titles before retiring as Tigers manager after the 2013 season.

His old adage still holds relevance today. The Twins enter 2020 ready to defend their division title, and they bulked up their already impressive lineup by signing free-agent slugger Josh Donaldson. But the key to their chances of holding off the still-lingering Indians and resurgent White Sox will almost surely be their rotation, which underwent some upgrades behind ace José Berríos.

Two of the top four rotations in the AL last year, in terms of fWAR, came from the Central. While Minnesota is a surprise in that respect, Cleveland is not. Detroit and Chicago have the pitching prospects to close the gap in a hurry, depending on when Michael Kopech, Casey Mize and Matt Manning crack the big leagues.

Here’s a team-by-team look at the AL Central starting staffs:

The best: Indians

Even without Corey Kluber, the Indians boast a rotation that has the potential to be one of the best in the league. The team returns Shane Bieber, who finished fourth in AL Cy Young Award voting in his sophomore campaign last year, and a fresh Mike Clevinger, who threw just 126 innings in 2019 due to an upper back strain, but still saw a 1.8 mph uptick in average fastball velocity from '18. And, after being diagnosed with leukemia last June, Carlos Carrasco is back to full health and is expected to return as a starter.

With those three right-handers sitting at the top of the rotation, the final two spots are still up for grabs. Zach Plesac and Aaron Civale thrived on the big stage in their rookie seasons in 2019 after they both began the year at Double-A Akron. The duo will join Adam Plutko as the favorites to earn the final two openings. It’s likely that Plutko will begin the year as a starter since he’s out of options. In that case, either Civale or Plesac would start the season at Triple-A Columbus, alongside lefties Scott Moss and Logan Allen, who will be depth pieces for the Tribe throughout the season.

The rest (in alphabetical order)

Royals
Kansas City's rotation is almost surely set through the first four spots with right-hander Brad Keller serving as the likely Opening Day starter. He is followed by left-hander Danny Duffy, right-hander Jakob Junis and lefty Mike Montgomery. Keller (165 1/3 innings) and Junis (175 1/3) are the workhorses. The interesting battle will be for the fifth spot. Royals general manager Dayton Moore has yet to add a veteran starter candidate and there is some belief in the organization that the Royals would be better off going with one of their young pitching prospects (Brady Singer, Daniel Lynch, Jackson Kowar, etc.) rather settling for a retread with less upside. The battle for that final starting job holds some intrigue.

Tigers
For now, Detroit will have to settle for having a case for the division’s best collection of pitching prospects, with Casey Mize, Matt Manning and Tarik Skubal -- all ranked among baseball’s top 50 prospects by MLB Pipeline -- expected to front a potentially loaded rotation at Triple-A Toledo. At the big league level, Matthew Boyd is a reliable third pitch away from joining the up-and-coming pitchers in the league, and he could become one of the coveted trade targets on the pitching market. Ivan Nova is a proven innings-eater signed off the free-agent market for stability. Jordan Zimmermann is hoping for a bounceback effort in the final season of the five-year contract he signed as a free agent in 2015. But the strength of Detroit’s rotation rests on Daniel Norris and Spencer Turnbull continuing to develop, and Michael Fulmer returning to form once he gets back to Detroit in the summer following Tommy John surgery last year.

Twins
The Twins might not have landed the front-of-rotation starter they initially sought at the start of the offseason, but they supplemented their splashy signing of Josh Donaldson by instead building out strong, experienced depth throughout their starting rotation. All-Stars José Berríos and Jake Odorizzi are both back to headline a largely underappreciated starting rotation from 2019 that was worth 16.6 WAR, per FanGraphs, the fourth-highest mark in the AL. The steady Michael Pineda is back to join them, and the Twins also acquired Homer Bailey, Rich Hill and reportedly Kenta Maeda to give themselves a deep mix of veteran experience and proven playoff success. Between those six and a host of young, in-house options, the Twins are primed to weather a long season and have plenty of flexibility for a possible playoff rotation.

Pineda (suspension) and Hill (left elbow surgery) will both miss the start of the season, which will give the Twins an opportunity to conduct a Spring Training competition between the likes of Randy Dobnak, Lewis Thorpe, Devin Smeltzer, Sean Poppen and non-roster invitee Jhoulys Chacín to fill an empty rotation spot -- and potentially find another diamond in the rough. On a Twins team that is largely set in every other roster grouping, keep an eye on the rotation as a group that should remain very fluid through September -- and possibly October.

White Sox
General manager Rick Hahn had an offseason target of strengthening the starting rotation, and he accomplished that goal through the free-agent additions of southpaws Dallas Keuchel and Gio González. They join a talented youthful trio of Lucas Giolito, Dylan Cease and Reynaldo López to begin the season. Giolito became one of the great success stories and great comeback stories of 2019, adjusting his mechanics, his mindset and his work process between starts to turn a rough ’18 campaign into being tied for sixth in AL Cy Young voting last year. The right-hander believes he has just scratched the surface in regards to the success he's reached via his new approach.

The White Sox ultimately might go as far as their young pitchers takes them. Cease’s numbers weren’t overwhelming in his 2019 debut season, though the right-hander did strike out 81 batters in 73 innings and he talked about feeling like a different pitcher at the end of the season from all he learned. López needs a return to his end-of-season form in ’18 after struggling in ’19, and the addition of Michael Kopech could be the biggest rotation boost of all. Kopech will gradually be worked back to the Majors after not pitching since September ’18 as he recovered from Tommy John surgery. Carlos Rodón also should be back in the picture by the season’s second half following his own Tommy John recovery.