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.

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