A dozen talented teams will enter the postseason with one goal in mind: a World Series championship. And thanks to perhaps a dangerous lineup or a formidable starting rotation or a lights-out bullpen, they are all confident that they can accomplish the goal. But even the best teams are never truly perfect.

Each club has something that might be the cause of its October downfall. We asked MLB.com's beat reporters for each of the playoff teams to identify that club's Achilles heel. Here is what they said.

AMERICAN LEAGUE

ORIOLES: Even though Baltimore used a six-man rotation for much of the second half, many of its young arms have pitched more this season than in any previous year of their pro careers, making fatigue a cause for concern. That includes the probable top two starters in the postseason rotation (Kyle Bradish and Grayson Rodriguez), All-Star reliever Yennier Cano and more. Still, the O’s will need to lean on these pitchers in October (especially Cano, with All-Star closer Félix Bautista out due to Tommy John surgery). The Orioles will hope these young pitchers don’t hit a wall the way Tyler Wells did in late July. -- Jake Rill

RAYS: Their elbows, hands, necks, obliques, knees and hamstrings. Injuries have wreaked havoc on this roster, testing even the Rays’ seemingly inexhaustible depth. Losing Shane McClanahan, Jeffrey Springs and Drew Rasmussen left their loaded rotation a bit top heavy, a potential issue in longer series. Recent injuries to Brandon Lowe, Luke Raley and Jose Siri turned role players into regulars and prospects into big leaguers. And they’re planning for the postseason without All-Star shortstop Wander Franco, who remains on indefinite administrative leave amid an MLB investigation. President of baseball operations Erik Neander called this the Rays’ most resilient team ever. They’ll have to prove it again in October. -- Adam Berry

BLUE JAYS: Can the Blue Jays come from behind against the quality of starters and relievers they’ll be seeing in October? We’ve seen this team thrive in tight games recently, but eventually, the Blue Jays need to win a slugfest, and their offense has been stuck in the middle of the pack. This offense is also built to string hits together and run the bases well, so its lack of power could make it difficult to land the big blows. Toronto’s lineup isn’t a “weakness” by any means, but if it’s asked to keep up with an offense like the Braves or Dodgers, the Blue Jays will be at a clear disadvantage. -- Keegan Matheson

TWINS: The Twins present the rare case of a team whose bullpen is in the best shape it’s been all season entering the postseason -- with a caveat. Four of the team’s key reinforcements down the stretch have great raw stuff in Louie Varland, Chris Paddack, Brock Stewart and Kenta Maeda. Here’s the thing, though: Varland is a career-long starter who is just learning to pitch in relief, Paddack hadn’t thrown a competitive pitch since last May, Stewart hadn’t pitched since June and Maeda hadn’t pitched in relief in four years. They’ll either sink or swim -- and they’re out of adjustment time. -- Do-Hyoung Park

ASTROS: The Astros rolled through the postseason last year on the strength of dominant pitching. They had so much starting-pitching depth that they put Luis Garcia and José Urquidy in the bullpen and barely used them in the playoffs. Houston has no such luxury this year, with Garcia and Lance McCullers Jr. out for the season and Cristian Javier having regressed. After Justin Verlander and Framber Valdez, the Astros’ starting pitching is very much a wild card. Javier will need to return to early-season form, and rookies J.P. France and Hunter Brown will have to show they’re up for the bright lights of October. -- Brian McTaggart

RANGERS: It’s a wonder that the Rangers have been as good as they have been all season long, given a bullpen that has felt historically bad at times. After another blown lead on Thursday, just one game away from clinching a postseason berth, Texas moved to just 30-for-63 (47.6%) in save opportunities this year, which is the lowest such mark in MLB. And though manager Bruce Bochy had a reputation as a bullpen guru before his first retirement, he’s never quite dealt with the struggles that Texas has presented. If anything keeps the Rangers from going deep into October, it’ll be their inability to win close games with a shutdown bullpen in the late innings. -- Kennedi Landry

NATIONAL LEAGUE

BRAVES: As the Braves rolled to a sixth straight National League East crown, the consensus was that the only things that could beat them would be themselves or injuries. Well, as this juggernaut progressed through the regular season’s final weekend, it placed both Max Fried and Charlie Morton on the injured list. Morton hopes to be ready if the Braves reach the NLCS. Fried will be available at the start of the NLDS, but there’s concern about how the blister on his left index finger might react. As good as the offense is, if Fried’s blister is a lingering issue, the Braves could be vulnerable to an early exit. -- Mark Bowman

PHILLIES: The Phillies’ bullpen has been a strength, but there have been enough signs of cracking down the stretch that the Phillies promoted rookie right-hander Orion Kerkering on Sept. 22. Kerkering is the Phillies’ No. 7 prospect, rising all the way from Single-A Clearwater at the beginning of the season. Why did Kerkering get the call? First, his stuff is nasty. Second, closer Craig Kimbrel has walked a tightrope the past few weeks, and right-hander Seranthony Domínguez hasn’t been his normal dominant self this season. The Phillies think Kerkering can tighten up things in the postseason. -- Todd Zolecki

MARLINS: If the Marlins were at full strength, their starting pitching could help them make a deep playoff run. Unfortunately, they will be without the services of reigning National League Cy Young Award winner Sandy Alcantara (right UCL sprain) and rookie Eury Pérez (left SI joint inflammation). Left-handers Jesús Luzardo and Braxton Garrett and right-hander Edward Cabrera are the club's only healthy starting pitchers. Veteran Johnny Cueto has been relegated to the bullpen due to ineffectiveness, while righty Bryan Hoeing is better suited for a long-relief role. That lack of depth would be tested in a long series. -- Christina De Nicola

BREWERS: The offense. The Brewers knew going into the season they would be driven by pitching and defense, and they made many decisions during the year that sacrificed run-scoring potential in the interest of run prevention. With an elite starting rotation, it was a trade they were willing to make. But it still takes runs to win, and it often takes home runs to win in the postseason, since the quality of opponents means it’s even more difficult than usual to string together base hits. The Brewers ranked tied for 24th of 30 teams in homers. It’s why they added Josh Donaldson in September. -- Adam McCalvy

DODGERS: The starting rotation. Having Bobby Miller and Clayton Kershaw as your top two options could certainly be worse, but Kershaw is still not 100 percent and will likely be limited, and Miller will be going through the rush of the postseason for the first time. But perhaps even more concerning is what the Dodgers will run out behind Kershaw and Miller. Lance Lynn has allowed homers at an alarming rate, and his role will be something the Dodgers will discuss before the NLDS. Ryan Pepiot and Emmet Sheehan have looked sharp and could be better options, but like Miller, they’ll be going through this for the first time. -- Juan Toribio

D-BACKS: The D-backs have a dominant front of the rotation in Zac Gallen and Merrill Kelly, but after that, it is far less established. Right-hander Brandon Pfaadt was the organization’s top pitching prospect when he arrived, and he has continued to improve as the year has rolled on after a rough beginning, but he’ll enter the postseason with 19 big league games (18 starts) under his belt. Ryne Nelson is another candidate to be the club’s third starter in the postseason, but he, too, has been up and down this year and is wrapping up his first full year in the big leagues. -- Steve Gilbert