In recent years, the trend has been for managers to keep their starting pitchers on a short leash, not being afraid to yank them when they get in even the slightest bit of trouble, even if it is only the third or fourth inning. This has placed an even greater emphasis on a team’s relief corps.

With the possibility of needing 15 or more outs, team’s will need length and depth from their relievers if they wish to make it far this postseason.

Bullpens will be the most important for teams playing in the win or go home American League Wild Card game, where the Yankees will take on the Athletics. Both teams have had a stellar showing from their bullpen this season, ranking second and third in the AL in earned run average (ERA).

Without an ace to put out, the A’s will likely be more reliant on their pen, led by closer Blake Treinen, sporting a shocking sub-one ERA. Yusmeiro Petit, Lou Trivino and Ryan Buchter have all been pleasant surprises to go along with mid-season acquisitions Fernando Rodney, Jeurys Familia and Shawn Kelley. Should their starter get in trouble, the A’s will have a strong relief core to try to piece them through the game.

As for the Yankees, they will either start Luis Severino, Masahiro Tanaka or JA Happ. Should one of them struggle, they do not have a long reliever to get six outs, but have Chad Green, Jonathan Holder, David Robertson, Zach Britton and Dellin Betances to bridge the game to their lights-out closer, Aroldis Chapman.

The key to advancing to the ALDS will be getting to the other team’s starter as scoring off the bullpen will not be easy.

The Astros have had a fantastic ‘pen all season, with four different relievers recording a save. With a stellar starting rotation, they may not need to be relied on as heavily as other teams, but would surely answer the call if need be.

A team on the other end of the spectrum is the Red Sox, who have not seen consistency outside of closer Craig Kimbrel. The Sox will need Joe Kelly, Matt Barnes or even knuckleballer Steven Wright to step and get outs late in the game.

The Indians by far have the worst ‘pen of any playoff team. Closer Cody Allen has struggled and they have been without relief-ace Andrew Miller on and off all season long. They acquired Brad Hand and Adam Cimber from the Padres and Cimber has looked like a completely different pitcher, struggling immensely. They have relied on journeymen Oliver Perez and Neil Ramirez to eat innings. They will need to be better as a whole to contend.

In the National League, the Cubs’ ‘pen has been struck by the injury bug, losing presumed closer Brandon Morrow to a biceps injury and fill-in Pedro Strop to a torn meniscus. The 2016 champs will have to rely on Steve Cishek and Jesse Chavez, who has thrived in late-inning roles thus far.

The Dodgers have faced their fair share of woes. Closer Kenley Jansen has not been himself due to health issues, and the team has yet to find a replacement for Morrow, who departed for Chicago in the offseason. The team has a lot of options, but none of them are overwhelming. Newly-acquired Ryan Madson, former starter Kenta Maeda and middle relievers Scott Alexander, Pedro Baez and Dylan Floro will be called on to bridge the gap to Jansen.

The Brewers bullpen could set them up for a team run. Josh Hader is perhaps the most unhittable pitcher in the league. Jeremy Jeffress has been sensational and closer Corey Knebel is returning to his 2017 all-star form. With shaky veteran starters, the Brew Crew may need to turn to these stud relievers earlier in games.

The Rockies spent big on their bullpen in the offseason and it has not paid off. They committed thirty million dollars to Wade Davis, Jake McGee and Bryan Shawn, who are all sporting ERA’s above four, with McGee’s and Shaw’s being over five. Though Adam Ottavino has been tremendous, this shaky, expensive group could cost the Rockies.

Despite this, it is the Braves with the worst group in the NL. While guys like AJ Minter and Dan Winkler have eaten innings, they have not been lights-out. The return of former closer Arodys Vizcaino should certainly boost the group’s prowess.

With the new emphasis on matchups on getting outs at any costs, having a strong and deep bullpen could be the x-factor to winning the World Series.