Bullpens are notoriously fickle. A shutdown pen one season can become a liability the next—sometimes with virtually the same group of pitchers—and vice versa.

Every year, once-reliable relievers fade and others rise from relative obscurity to pitch lights-out in the late innings.

With those caveats in mind, let's rank all 30 MLB teams' bullpens heading (hopefully) into the still-uncertain 2020 MLB season.

Elite closers matter, obviously, but we also considered depth. Is there a top-notch setup man or two ready to assume ninth-inning duties as needed? And how much coverage is there for the less glamorous but nonetheless essential middle innings?

The Bottom 10

30. Seattle Mariners

Yoshihisa Hirano posted a 4.75 ERA last season with the Arizona Diamondbacks and has saved four games in his MLB career. He's the presumed closer for the Mariners. It doesn't get much better after that with a mishmash of young question marks and struggling veterans in the pen for what should be a last-place M's club. 

29. Baltimore Orioles

There's hope surrounding converted starter Hunter Harvey, who flashed a high-90s fastball out of the bullpen for the Orioles last season. Veteran Mychal Givens led all O's relievers who pitched 10 innings or more with a 4.57 ERA and averaged 12.3 strikeouts per nine innings. He figures to be trade bait. The rest of Baltimore's bullpen will be a liability, like much of the rest of its roster. 

28. Pittsburgh Pirates

The Pirates placed closer Felipe Vazquez on the restricted list last September after he was charged with statutory sexual assault, unlawful contact with a minor and corruption of a minor, among other charges (he was later charged with 21 additional counts in the case). Keone Kela saved 24 games in 2018 with the Texas Rangers and should take over closer duties. After that, it's an uninspiring collection of guys like Kyle Crick, Richard Rodriguez and Michael Feliz, who combined for minus-0.9 WAR in 2019.   

27. Detroit Tigers

Joe Jimenez nailed down nine saves last season after the Tigers traded Shane Greene to the Atlanta Braves in July, and Jimenez averaged 12.4 K/9 overall, albeit with a 4.66 FIP. Detroit ranked 24th in baseball with a 4.94 bullpen ERA in 2019, and the group behind Jimenez doesn't appear primed to improve on that mark.   

26. Miami Marlins

The Marlins made some decent additions to a dreadful bullpen this offseason, signing right-handers Brandon Kintzler (2.68 ERA) and Yimi Garcia (3.61). Neither will turn Miami's relief corps into a powerhouse, but they should stabilize a unit that ranked 25th with a 4.97 ERA and converted just 27 of 49 save opportunities.   

25. San Francisco Giants

After San Francisco traded Mark Melancon to the Braves at the 2019 deadline and waved goodbye to closer Will Smith via free agency, the Giants bullpen should go from a strength to a weakness. Trevor Gott and Tony Watson could see ninth-inning action, but both posted ERAs above 4.00 last season, and Watson battled shoulder soreness in the spring. Expect San Francisco to audition a lot of arms and see who sticks. 

24. Philadelphia Phillies

After a terrible 2018, Phillies closer Hector Neris posted a 2.93 ERA with 28 saves last season for Philadelphia. The group behind him is thin, though the Phils could get a boost from Vince Velasquez. Assuming he doesn't make the starting rotation, Velasquez's power arm and strikeout stuff could play well in the late innings.   

23. Texas Rangers

Presumed closer Jose LeClerc posted a 1.56 ERA in 2018 but saw that number balloon to 4.33 last season. The rest of the Rangers pen is equally uncertain. Rafael Montero returned from Tommy John surgery to post a 2.48 ERA in 29 innings in 2019. Joely Rodriguez posted a 6.33 ERA for the Phillies in 2017 but is returning to the majors after two dominant seasons in Japan, during which he posted a 1.85 ERA with 10.5 K/9.   

22. Colorado Rockies

The Rockies are banking on a bounce-back from veteran closer Wade Davis. After saving 43 games in 2018, Davis gave up 41 earned runs in 42.2 innings last season. If he's that bad again, the Rox's bullpen is probably sunk, though Scott Oberg (2.25 ERA, 9.3 K/9) is an interesting option and could assume ninth-inning duties. Beyond that, there's not much depth in Colorado, where pitchers routinely get punished.   

21. Kansas City Royals

Transitioning to the bullpen after 12 seasons as a starter, Ian Kennedy saved 30 games and posted a 3.41 ERA last year, though he struggled in stretches. Veterans Greg Holland and Trevor Rosenthal have 327 career saves between them, but both have struggled with command since coming back from Tommy John surgery. Kansas City's unit doesn't lack experience, but enough questions exist to keep it in the bottom 10.

The Middle 10

20. Los Angeles Angels

Hansel Robles emerged as an above-average closer for the Angels in 2019, notching 23 saves with a 2.48 ERA. His 2.0 BB/9 could stand improvement, but the ninth inning should be covered. After that? Eh. Setup man Ty Buttrey posted a ho-hum 3.98 ERA; Keynan Middleton pitched limited innings last season after returning from 2018 Tommy John surgery; and there aren't any other obvious late-inning arms.

19. Chicago Cubs

After waiting until June to sign with the Chicago Cubs, closer Craig Kimbrel posted a 6.53 ERA and allowed nine home runs in 20.2 innings. He notched 30 strikeouts and showed flashes of his All-Star self, but clearly the 32-year-old needs to bounce back significantly. Lefty Kyle Ryan was solid in 73 appearances for Chicago. Righty Rowan Wick (2.43 ERA) could assume setup duties, and veterans Tyler Chatwood and Jeremy Jeffress provide depth.   

18. Cincinnati Reds

The Reds bullpen could shoot up these rankings if they get comeback seasons from closer Raisel Iglesias and setup man Pedro Strop. Both have strong track records, but they posted unsightly ERAs of 4.16 and 4.97, respectively, in 2019. Michael Lorenzen and Amir Garrett were steady for Cincinnati, but the bullpen's fortunes rest on the performance of its late-inning duo.

17. Boston Red Sox

After beginning the season with a closer-by-committee approach, the Boston Red Sox turned increasingly to Brandon Workman for ninth-inning duties down the stretch. The 31-year-old had a massive breakout, as his K/9 jumped from 8.1 in 2018 to 13.1, and he shaved his ERA from 3.21 to 1.88. Is it sustainable? We'll find out. Behind him, setup man Matt Barnes, as well as Ryan Brasier, Marcus Walden and Heath Hembree provide late-inning depth. 

16. New York Mets

Mets closer Edwin Diaz allowed 15 home runs in 58 innings last season and finished with a 5.59 ERA, while setup man Jeurys Familia issued 42 walks in 60 innings and posted a 5.70 ERA. They fronted a bullpen that was mostly a disaster outside Seth Lugo (2.70 ERA, 11.7 K/9). The addition of free agent Dellin Betances should improve things, as he'll join Lugo to form a potent late-inning combo. If Diaz can get his long-ball-surrendering tendencies under control, this unit could be much-improved.

15. Toronto Blue Jays

Closer Ken Giles was superb for the Blue Jays in 2019, converting 23 of 24 save opportunities with a 1.87 ERA and 14.1 K/9. He'll be a free agent after the 2020 campaign, but assuming the season happens, the Jays could dangle him to a contender as a relief rental. If they do, there isn't a clear heir apparent for ninth-inning duties. Anthony Bass posted a 3.56 ERA for Seattle in 2019 and should be the primary setup man. Rafael Dolis and Shun Yamaguchi also join the mix after successful stints in Japan.

14. St. Louis Cardinals

The state of the Cardinals bullpen depends largely on two pitchers: Andrew Miller and Jordan Hicks. Once among the most lights-out lefty relievers in the game, Miller has been a bit off his game since last season and has struggled with control. The hard-throwing Hicks, meanwhile, is coming back from Tommy John surgery. If both players return healthy and effective, they'll join a solid relief corps that includes Giovanny Gallegos, John Gant, John Brebbia, Ryan Helsley and Carlos Martinez, assuming he doesn't return to the rotation.

13. Chicago White Sox

Alex Colome, Aaron Bummer, Steve Cishek, Evan Marshall and Jimmy Cordero figure to eat up a lot of relief innings for the White Sox, and all posted ERAs below 3.00 in 2019. Then there's Kelvin Herrera, who was an elite bullpen arm from 2011 to 2018 before posting a 6.14 ERA in his first season on the South Side. If he rebounds, this could be one of the deeper units in baseball.

12. Cleveland Indians

Brad Hand continued to be one of the game's best closers in 2019, notching a career-high 34 saves with a 2.80 FIP and 13.2 K/9. Behind him, Nick Wittgren, Oliver Perez, Adam Cimber and James Hoyt fill out a bullpen that finished third in MLB with a 3.76 ERA last season and should again be a strength for the Indians.

11. Arizona Diamondbacks

Archie Bradley struggled early last season in middle relief but proved himself after the Diamondbacks gave him the closer's gig in July. He finished with 18 saves and a career-best 10.9 K/9 and posted a 1.47 ERA over his last 34 appearances. After that, Junior Guerra, Andrew Chafin and Hector Rondon all posted sub-4.00 ERAs. And 26-year-old Kevin Ginkel could be another weapon after posting a 1.48 ERA and 10.4 K/9 in 24.1 innings as a rookie.

10. Washington Nationals

The bullpen was a weakness in the early going for the Washington Nationals last season, but it should be a strength for the defending champs in 2020.

Will Harris, who posted a 1.50 ERA in 60 innings for the Houston Astros in 2019, will join the excellent late-inning trio of Sean Doolittle, Daniel Hudson and Roenis Elias.

Add right-hander Tanner Rainey, who struck out 74 in 48.1 innings for Washington, and you've got a pen that will more than support the Nats' superlative starting rotation.

9. Los Angeles Dodgers

Closer Kenley Jansen posted a career-worst 3.71 ERA in 2019. His days as one of the sport's top closers may be numbered. Still, he saved 33 games with 11.4 K/9 for the Los Angeles Dodgers.

Behind him, Pedro Baez (3.10 ERA in 69.2 innings) is among the more reliable setup men in the league. Then there's the newly arrived Blake Treinen.

After posting a minuscule 0.78 ERA with 38 saves in 2018 for the Oakland Athletics, Treinen saw his ERA jump to 4.91 in 2019, and he was relieved of ninth-inning duties. If the 31-year-old can return to anything resembling his '18 form, Los Angeles could have one of the best late-inning trios in baseball.

8. Atlanta Braves

Mark Melancon will probably serve as the Atlanta Braves' primary closer, but Atlanta has plenty of options.

Will Smith, Shane Greene and Luke Jackson each recorded 18 or more saves in 2019. The left-handed Smith (2.76 ERA, 13.2 K/9) was an All-Star closer for the San Francisco Giants, and Greene, also an All-Star, saved 22 games with a 1.18 ERA for the Tigers before a midseason trade to the Braves.

Really, if any team is going to hand the ninth inning over to a committee, it should be Atlanta, which boasts one of the most experienced, proven pens in the game. 

7. Houston Astros

Roberto Osuna saved 38 games with a 2.63 ERA and 10.1 K/9 for the Houston Astros in 2019 and continued his run as a top-tier closer. Ryan Pressly (2.32 ERA) and Joe Smith (1.80 ERA) join Osuna to form a potent trifecta.

The 'Stros lost Harris, Hector Rondon and Collin McHugh to free agency. That could damage their bullpen depth.

But with Bryan Abreu, Josh James and Brad Peacock likely part of a battle for one open spot in the starting rotation, two of those arms could help flesh out Houston's excellent relief corps.

6. Minnesota Twins

The Minnesota Twins gave lefty Taylor Rogers the ninth inning in 2019, and he responded with 30 saves, 90 strikeouts and a 2.61 ERA in 69 innings.

Tyler Duffey and Trevor May thrived in Minnesota's bullpen in 2019 and will be joined by veterans Tyler Clippard (2.90 ERA) and Sergio Romo (3.43 ERA), both of whom have closing experience.

Assuming Rogers repeats his success and Romo and Clippard have gas left, this figures to be a deep, versatile group for the Twinkies.

5. Tampa Bay Rays

If you're looking for an about-to-explode star closer, look no further than Nick Anderson.

The 29-year-old tallied just one save in his rookie season in 2019 but struck out 110 in 65 innings with the Marlins and Tampa Bay Rays and finished with a 2.35 FIP.

Colin Poche, who fanned 72 in 51.2 innings as a rookie in 2019, is another rising star reliever to watch in Tampa Bay.

Add the solid lefty-righty duo of Diego Castillo and Jose Alvarado, and the Rays' relievers should be a force on a club that helped pioneer the opener and is all too happy to turn to its pen.

4. Oakland Athletics

After Treinen lost the ninth-inning job, the Oakland Athletics handed the reins to Liam Hendriks in June. He did not disappoint.

Hendriks finished the year with 3.8 WAR, tops among all relief pitchers, while posting a 1.80 ERA with 13.1 K/9 in 85 innings. It was easily a career year for the 31-year-old, and he could regress as Treinen did, but for now he's one of MLB's top closers.

Yusmeiro Petit was a strong setup man with 80 appearances, 83 innings, a 2.71 ERA and impressive 7.1 K/BB ratio.

Veteran Joakim Soria has 221 career saves and posted a 3.62 FIP and 10.3 K/9, making him one of the more overqualified seventh-inning options in baseball.

3. Milwaukee Brewers

Josh Hader has been devastating each of the past two seasons with the Milwaukee Brewers, posting WHIPs of 0.81 in both 2018 and 2019 and K/9s of 15.8 and 16.4. Add his 37 saves in '19, and the 26-year-old lefty has a case as the best closer in the game.

Behind him, former starter Brent Suter returned from Tommy John surgery to post a 0.49 ERA in 18.1 innings and could be a force out of the bullpen over a full season.

Former Milwaukee closer Corey Knebel is also coming back from Tommy John, but he should be available by Opening Day, whenever that will be. If Knebel rediscovers the stuff that helped him post a 1.78 ERA with 14.9 K/9 in 2017, the Crew might have the best pen in baseball.

2. San Diego Padres

If Hader isn't the best closer in MLB, the title belongs to the San Diego Padres' Kirby Yates. The right-hander led the game with 41 saves in 2019, and he posted a 1.19 ERA and 15.0 K/9 while earning an All-Star nod and finishing ninth in the NL Cy Young Award balloting.

The Pads added a stellar setup man in Emilio Pagan, who posted a 2.31 ERA with 20 saves for the Rays last season.

Toss in right-hander Craig Stammen (3.29 ERA in 82 innings) and lefty Drew Pomeranz (2.39 ERA in 26.1 innings with the Brewers), and San Diego's relief corps should thrive in pitcher-friendly Petco Park.

1. New York Yankees

Despite losing Betances to the Mets, the New York Yankees own MLB's best bullpen until further notice.

It begins with hard-throwing closer Aroldis Chapman, who posted a 2.21 ERA with 37 saves and struck out 85 in 57 innings in 2019.

After that, Zack Britton, Adam Ottavino and Tommy Kahnle round out an impressive Big Four. Britton and Ottavino each posted sub-2.00 ERAs last season, while Kahnle averaged 12.9 K/9 and threw high-leverage innings in the postseason.

When necessary, the Yankees' relievers can shorten games significantly, which is what all great bullpens do.

All statistics courtesy of Baseball Reference.