These were the best relievers in baseball all season. But who was the best of the best?

The finalists for the 2020 American and National League Relievers of the Year presented by The Hartford were announced Monday. There are three finalists in each league, with the American League winner named the Mariano Rivera AL Reliever of the Year and the National League winner named the Trevor Hoffman NL Reliever of the Year. Last year's award winners were Aroldis Chapman in the AL and Josh Hader in the NL.

• Past Reliever of the Year winners

This year, the AL finalists are Alex Colomé of the White Sox, Brad Hand of the Indians and Liam Hendriks of the A's. The NL finalists are Jeremy Jeffress of the Cubs, Trevor Rosenthal of the Padres and Devin Williams of the Brewers. That guarantees a first-time winner in both leagues.

Here's a Reliever of the Year case for each of the six:

Mariano Rivera AL Reliever of the Year

Alex Colomé, White Sox
Colomé locked down the ninth inning for the White Sox on their run to their first postseason appearance since 2008. The 31-year-old right-hander ranked tied for third in the AL and tied for fourth in the Majors with 12 saves, and his 0.81 ERA was the second lowest in the AL and fourth lowest in MLB among qualifying relievers. Eighteen of Colomé's 21 appearances were scoreless.

Brad Hand, Indians
Hand led the Major Leagues in saves with 16 for Cleveland, and he also finished the most games (21) of any AL reliever. The veteran left-hander didn't blow a single save all season as the Tribe made the playoffs for the fourth time in the last five years.

Hand also posted a 2.05 ERA and had 29 strikeouts in 22 innings.

Liam Hendriks, A's
Hendriks finished second in the Majors with 14 saves. The right-hander was the hardest reliever in the league to reach base against, with a 0.671 WHIP that was the lowest among AL relievers. Hendriks also had a 1.78 ERA and 37 strikeouts, tied for fifth most among AL relievers. The 31-year-old was every bit as lights-out in 2020 as he was in his All-Star '19, when he had a 1.80 ERA and an identical 13.1 strikeouts per nine innings.

Trevor Hoffman NL Reliever of the Year

Jeremy Jeffress, Cubs
Jeffress stepped up big for the Cubs after signing with them as a free agent in February. He took over the closer role for Craig Kimbrel, finishing with a 1.54 ERA and eight saves in his 22 relief appearances as Chicago returned to the postseason after missing out in 2019.

It was a huge bounce-back season for the 33-year-old right-hander, who had a 5.02 ERA in '19 as he struggled with injuries and was even released by the Brewers in September.

Trevor Rosenthal, Padres
Rosenthal had a remarkable comeback in 2020, overcoming his extreme control issues from '19 to return to his old dominant form. A year ago, Rosenthal had a 13.50 ERA with 26 walks to 17 strikeouts in 15 1/3 innings. This year? A 1.90 ERA and 38 strikeouts to eight walks in 23 2/3 innings. After his trade from the Royals to the Padres, Rosenthal didn't allow an earned run and totaled 17 strikeouts to just one walk in 10 innings. Firing his 100-plus mph fastballs, Rosenthal picked up four of his 11 saves for playoff-bound San Diego.

Devin Williams, Brewers
Williams broke out in 2020 as MLB's nastiest reliever, thanks to a devastating "airbender" changeup that might have been the best pitch in baseball. The 26-year-old right-hander struck out over half of the batters he faced, setting an MLB single-season record for relievers with his 53.0 percent strikeout rate (surpassing Chapman's 52.5 percent mark in '14). Williams led MLB relievers in both ERA (0.33) and strikeouts (53, tied with the Indians' James Karinchak). Those 53 strikeouts came in just 27 innings over 22 relief appearances.