Mariano Rivera is the best closer of all-time, but who had the best season as a reliever?
A dominant bullpen can carry a team a long way, yet relievers often take a back seat to the starting rotation and the batting order.
In 2011, several relievers had phenomenal campaigns.
Mariano Rivera, who surpassed Trevor Hoffman for the No. 1 spot on the all-time saves list, had a very strong 2011—but was he the best reliever in baseball?
These are the 15 best relief pitchers of 2011.
The only prerequisite—a minimum of 50 innings pitched.
Also, I barely considered wins above replacement (WAR), because the difference between each relief pitcher's WAR really is minuscule.
As the Philadelphia Phillies' closer, Ryan Madson had a very solid 2011 campaign.
Madson converted 32 of 34 save opportunities, posting a 2.37 ERA and 1.15 WHIP along the way.
Opposing hitters held a .243 batting average against Madson, who fanned 62 batters in 60.2 innings of work.
In his first season with the Los Angeles Angels, Scott Downs had the best year of his career.
Acting as a setup man, Downs held 26 games while posting a 1.34 ERA and a 1.01 WHIP in 53.2 innings.
Opponents hit just .199 against Downs.
Jonathan Papelbon blew a save in Boston's final game of 2011.
Had the Red Sox maintained their 3-2 lead over the Baltimore Orioles, they would have played Tampa Bay in a one-game playoff for the AL Wild Card.
That blown save is an indelible taint on Papelbon's 2011 campaign, but his season should not be defined by one outing.
Papelbon saved 31 games in 34 opportunities, posting a 0.93 WHIP, a .207 BAA and 12.17 K/9 ratio.
His 2.94 ERA is the highest on this list, but he had a great second half, in which he had a 1.63 ERA and .144 BAA.
Although Kyle Farnsworth's strikeout rate declined in 2011, the Tampa Bay Rays' "unofficial" closer had the second-best season of his career.
Farnsworth bounced back from a rough second half with Atlanta in 2010 to save 25 games in 31 opportunities for the Rays.
The flame-throwing righty posted a 2.18 ERA and a 0.99 WHIP while opponents hit just .211 off him.
Farnsworth struck out 51 batters in 57.2 innings.
A rough September tainted what had been a tremendous season by Atlanta's Jonny Venters.
However, his 5.11 September ERA can certainly be attributed, at least partially, to overwork—the southpaw tossed 88 innings for Fredi Gonzalez.
Even with his poor performance in the season's final month, Venters posted a 1.84 ERA and 1.09 WHIP in 2011. He struck out 96 batters, who hit just .176 against him.
In 73.2 innings, Eric O'Flaherty allowed just eight earned runs—good for a microscopic 0.98 ERA.
The lefty posted a 1.09 WHIP and .221 BAA, and he fanned 67 batters as part of the bridge to Craig Kimbrel.
Tyler Clippard perpetually flustered the opposition in 2011, as evidenced by his 0.84 WHIP and .162 BAA.
His 1.83 ERA is largely the result of the 11 homers he surrendered.
In 88.1 innings, Clippard fanned 104 hitters.
In his first season in Arizona, J.J. Putz converted 45 of his 49 save opportunities and posted a 2.17 ERA, 0.91 WHIP and .195 BAA.
The veteran right-hander struck out just over one batter per inning.
Putz didn't fare well in June, when he had a 6.17 ERA, but otherwise he was extremely reliable.
Pittsburgh managed to stay in contention for the first half of the season, thanks to Joel Hanrahan.
Even when the team began to falter, Hanrahan remained relatively stable.
The closer posted a 1.83 ERA, 1.05 WHIP and .220 BAA and converted 40 of his 44 save opportunities.
Mike Adams became one of the hottest commodities on the trade market, mowing down the opposition as a member of the San Diego Padres.
As Heath Bell's setup man, Adams posted a 1.13 ERA and 0.73 WHIP. His opponents hit just .155.
After arriving in Texas at the trade deadline, Adams continued his dominance—to a lesser degree.
Adams' 2.10 ERA, 0.90 WHIP and .196 BAA in Texas raised his 2011 numbers to 1.47, 0.79 and .169—still phenomenal.
Adams struck out just over one batter per inning.
John Axford had a shaky start to 2011 but had a dominant second half.
The Brewers' closer surrendered three earned runs in 32.1 second-half innings for a 0.84 ERA.
Overall, Axford had a 1.95 ERA, 1.14 WHIP and .212 BAA. He also fanned 86 batters in 73.2 innings while converting 46 of 48 save opportunities.
Jose Valverde converted all 49 save opportunities, but he wasn't perfect—he still lost four games.
The Tigers' closer has a tendency of making the game exciting by putting runners on base.
His 1.19 WHIP is the highest of any reliever on this list.
Still, Valverde had a very strong season, posting a 2.24 ERA and striking out 69 batters in 72.1 innings.
Mariano Rivera, as usual, used his immaculate control to keep runners off base—he walked just eight batters, resulting in a 0.90 WHIP.
Although opposing hitters batted .215 against Rivera, the all-time saves leader generally prevented them from scoring and posted a 1.91 ERA.
Mo converted 44 of 49 save opportunities.
Craig Kimbrel was baseball's most overpowering reliever this season, striking out 127 batters in 77 innings.
Although he faltered down the stretch, Kimbrel's 2.10 ERA, 1.04 WHIP and .178 BAA are all very impressive.
He did blow eight saves, including three in September, but he also saved 46.
David Robertson thrived as Mariano Rivera's setup man, usurping the title from Rafael Soriano early in the season.
The 26-year-old allowed just eight earned runs while striking out 100 batters in 66.2 innings—that calculates to a 1.08 ERA and 13.5 K/9 rate, for your information.
Robertson occasionally struggled with his control, walking 35 batters. However, opponents rarely recorded a big hit against him—he surrendered one home run and had a .170 BAA.
Robertson's ERA never exceeded 1.93, and opponents amassed just three earned runs and hit just .144 off him in the second half.
He was the most consistent, reliable reliever in baseball.