As always, feel free to contribute your own top 10 in the comments section below.
10. Royals: Other than the Rockies, who put their starters on a 75-pitch limit at midseason, no relief unit was called upon more in 2012 than that of the Royals, who logged 561 1/3 innings out of their bullpen. With a 3.17 ERA that ranked sixth in the sport, it was a very effective unit, even with formerly dominant closer Joakim Soria on the shelf. Greg Holland stepped into the closer role and struck out 91 batters in 67 innings, and he's supported by fellow hard throwers Kelvin Herrera and Aaron Crow. Tiny Tim Collins struck out 93 in 69 2/3 innings. This is a deep, power staff that shouldn't have to carry as much of the load now that the Royals have seemingly improved their rotation.
9. Yankees: Mariano Rivera is the best closer in baseball until he isn't. Last year, he wasn't, for the obvious reason that he wasn't active. Now that he is active, I'll believe he'll remain highly effective until my eyes tell me otherwise. He is, however, 43 years old, so this won't go on forever (or will it?). Because of Rivera's return and the presence of fellow relief ace David Robertson, with upside in the form of Cody Eppley and Mark Montgomery, I'll give Mo the benefit of the doubt and give the Yanks, who rated No. 1 on this list a year ago, a spot in the top 10, even with Rafael Soriano out of the picture.
8. Dodgers: With a relief ERA of 3.19, which ranked seventh in the Majors last season, and a relief average against of .221, which ranked fourth, the Dodgers already had a solid mix. They added Brandon League at the Trade Deadline last year, and he'll be the closer in 2013, and they added a nice left-handed option in J.P. Howell, who made big strides in his return from shoulder surgery last season. Kenley Jansen, who struck out 99 in 65 innings last season despite an irregular heartbeat that led to offseason surgery, is a legitimate closing candidate in his own right.
7. Reds: The Reds had arguably the best bullpen in baseball last season, but obviously Aroldis Chapman was a big, big part of that success. The Reds' decision to convert him to starting work probably makes sense for the long-term, but it figures to take some of the shine off this unit in the present tense. Jonathan Broxton will take over the ninth after a solid bounceback season. Sean Marshall, Jose Arredondo, Sam LeCure and Logan Ondrusek all return to what is a very solid relief corps that can and should again be among the best in the game. But there's little question that Chapman's move will have an impact.
6. A's: Though the A's traded their one-time All-Star closer, Andrew Bailey, before the 2012 season, they found a lockdown late-inning tandem of veteran Grant Balfour (0.924 WHIP) and rookie Ryan Cook (0.941). Lefty Sean Doolittle was a revelation, an effective left-on-left matchup man in MLB less than a year after converting from first base. The A's return all the principles of their 'pen, so they should again have the solid support of one of the league's best rotations.
5. Giants: Last season was actually a down one for a Giants bullpen that had finished second in the Majors in relief ERA each of the previous three years. In 2012, with Brian Wilson out of the picture, a still-respectable 3.56 mark ranked 15th. But by year's end, the 'pen was once again a major, major strength, with Sergio Romo emerging from a committee of closers to shine in the ninth inning during the October run. Because Romo relies so heavily on his breaking pitches, it's possible his workload will be more measured than that of the average closer, and that's why having setup men Jeremy Affeldt and Santiago Casilla, both of whom can close games, is so vital.
4. Orioles: There is no easy way to describe the Orioles' ridiculous season, but suffice to say it doesn't happen without this particularly bullish bullpen -- a unit that ranked fifth in the Majors in relief ERA with an even 3.00 mark. That was a big reason the O's went an unprecedented 29-9 in one-run games. The relievers also held up to the rigors of a substantial workload, as they were turned to for 545 1/3 innings, fourth-most of any team in baseball and the most of any playoff team. Closer Jim Johnson saved 51 games and allowed just three homers and 15 walks in 68 2/3 innings. Setup men Pedro Strop and Darren O'Day return, and it will be interesting to see if Brian Matusz and/or Tommy Hunter, struggling starters who flourished in a relief role late last year, will wind up back in the bullpen mix at any point.
3. Nationals: The Nats already had two relievers with recent 30-plus save seasons in their back-end mix for 2013, and then they added another in dramatic fashion by signing Rafael Soriano, who saved 42 games for the Yankees last year. Soriano will take over as the closer, and the Nats seem to have insured themselves against the volatility of late-inning relief. That volatility revealed itself in stunning fashion in Game 5 of last year's Division Series, but this had been a very reliable unit prior to that point, ranking eighth in relief ERA. Soriano's arrival puts the Nats in position to have a truly elite bullpen.
2. Rays: Certain things are tradition this time of year. Groundhog Day. The Super Bowl. Valentine's Day. Pitchers and catchers reporting. The Rays somehow putting an elite bullpen together. I foolishly didn't have them in this top 10 a year ago, because I had the same questions about the Rays' closing situation as anybody. But Fernando Rodney responded in a big way -- 48 saves and a 0.60 ERA that was the lowest in history. And as a unit, the Rays had the lowest relief ERA (2.88) in the American League in seven years. Young left-hander Jake McGee made huge developmental strides and posted a 1.95 ERA. Joel Peralta, Kyle Farnsworth and Cesar Ramos should make for an effective setup group, and a move to the bullpen could be good for the command issues that have plagued Roberto Hernandez (The Artist Formerly Known As Fausto Carmona) in recent years. There are questions here -- particularly about Rodney's ability to repeat his 2012 performance and the starting-innings stability lost by trading James Shields -- but the Rays typically find ways to answer the questions in this area.
1. Braves: One of the few no-brainers in compiling these lists is putting the Braves here. Closer Craig Kimbrel wasn't just good but historically good last season, and, as I argued in November, should have received stronger Cy Young consideration. Kimbrel had an unprecedented 16.7 strikeouts-per-nine-innings ratio and held the opposition to a .128 average. And his supporting cast is pretty darned good, too. Jonny Venters, perhaps predictably after especially heavy workloads in 2010 and '11, struggled in the first half but had a 1.71 ERA in the second. Eric O'Flaherty has a 1.31 ERA over the past two seasons. The 23-year-old Luis Avilan arrived and had a 2.00 ERA and 33 strikeouts in 36 innings. And if the Braves are able to straighten out Jordan Walden's command, the best bullpen in baseball could get even better.
Honorable mention: General manager John Mozeliak once again did an impressive patch-up job on the Cardinals' bullpen at midseason, as Ed Mujica proved to be an impactful acquisition to what had been an erratic relief corps. ... The D-backs will have an elite 'pen if J.J. Putz remains healthy and Heath Bell bounces back. ... The Mariners had five guys finish 2012 with more than 10 strikeouts per nine, and that group doesn't even include underrated closer Tom Wilhelmsen. ... The addition of Mike Adams should help the Phillies get late leads into the hands of Jonathan Papelbon. ... The Red Sox could very quickly ascend in the bullpen ranks, depending on Joel Hanrahan's transition and whether Andrew Bailey and Daniel Bard can recapture their 2011 forms. ... The additions of Matt Albers and Matt Capps should further strengthen an Indians bullpen whose closer (Chris Perez) finished eighth in save percentage and whose setup man (Vinnie Pestano) finished second in holds. ... The Padres' bullpen, which ranked ninth in relief ERA last year, should be good again if Huston Street stays healthy. ... Yeah, there are a lot of teams listed here. Bullpens are absolutely unpredictable and a nightmare to rank.