Updated June 1, 2021
| AL East | Closer | Job Security | Tier | Next up | Wild card |
| Baltimore Orioles | Cesar Valdez | + | 4 | Paul Fry | Hunter Harvey |
| Boston Red Sox | Matt Barnes | +++ | 2 | Adam Ottavino | Hirokazu Sawamura |
| New York Yankees | Aroldis Chapman | +++ | 1 | Chad Green | Jonathan Loaisiga |
| Tampa Bay Rays | J.P. Feyereisen (committe) | ++ | 3 | Diego Castillo | Pete Fairbanks |
| Toronto Blue Jays | Jordan Romano | ++ | 3 | Rafael Dolis | Tyler Chatwood |
| AL Central | |||||
| Chicago White Sox | Liam Hendriks | +++ | 2 | Aaron Bummer | Evan Marshall |
| Cleveland Indians | James Karinchak (committee) | ++ | 3 | Emmanuel Clase | Nick Wittgren |
| Detroit Tigers | Michael Fulmer | + | 3 | Gregory Soto | Jose Cisnero |
| Kansas City Royals | Kyle Zimmer (committee) | + | 3 | Greg Holland | Scott Barlow |
| Minnesota Twins | Taylor Rogers (committee) | + | 4 | Hansel Robles | Alex Colome |
| AL West | |||||
| Houston Astros | Ryan Pressly | ++ | 3 | Ryne Stanek | Bryan Abreu |
| Los Angeles Angels | Raisel Iglesias | +++ | 3 | Mike Mayers | Tony Watson |
| Oakland Athletics | Joe Trivino (committee) | +++ | 3 | Jake Diekman | Yusmeiro Petit |
| Seattle Mariners | Rafael Montero (committee) | + | 4 | Keynan Middleton | Kendall Graveman |
| Texas Rangers | Ian Kennedy | ++ | 3 | Joely Rodriguez | Josh Sborz |
| NL East | |||||
| Atlanta Braves | Will Smith | ++ | 3 | Chris Martin | Shane Greene |
| Miami Marlins | Yimi Garcia | ++ | 3 | Dylan Floro | Anthony Bass |
| New York Mets | Edwin Diaz | +++ | 3 | Trevor May | Seth Lugo |
| Philadelphia Phillies | Hector Neris | ++ | 3 | Jose Alvarado | Sam Coonrod |
| Washington Nationals | Brad Hand | ++ | 3 | Daniel Hudson | Tanner Rainey |
| NL Central | |||||
| Chicago Cubs | Craig Kimbrel | +++ | 2 | Andrew Chafin | Ryan Tepera |
| Cincinnati Reds | Lucas Sims (committee) | + | 3 | Tejay Antone | Amir Garrett |
| Milwaukee Brewers | Josh Hader | +++ | 1 | Devin Williams | Brad Boxberger |
| Pittsburgh Pirates | Richard Rodriguez | ++ | 3 | David Bednar | Kyle Crick |
| St. Louis Cardinals | Alex Reyes | +++ | 2 | Giovanny Gallegos | Genesis Cabrera |
| NL West | |||||
| Arizona Diamondbacks | Stefan Crichton | + | 5 | Joakim Soria | Kevin Ginkel |
| Colorado Rockies | Daniel Bard | + | 5 | Carlos Estevez | Mychal Givens |
| Los Angeles Dodgers | Kenley Jansen | +++ | 2 | Blake Treinen | Victor Gonzalez |
| San Diego Padres | Mark Melancon | +++ | 2 | Emilio Pagan | Craig Stammen |
| San Francisco Giants | Tyler Rogers (committee) | + | 3 | Jake McGee | Matt Wisler |