Here is a detailed look at each relief pitcher in the American League with fantasy baseball significance as a closer or one who could assume the job down the road. This analysis, along with similar work in the National League Tiers or Relief Pitching, helped form my final mixed league closer rankings.

 
Tier 1 ($20+)*

* Dollar values represent estimates for AL-only leagues

Joakim Soria, KC – Even with the shoulder soreness he experienced last spring, Soria saved a career-high 43 games and struck out 9.73 batters per 9 innings – compiling a 1.78 ERA and 1.05 WHIP. Perhaps most significantly, he induced groundballs 48% of the time and kept his xFIP under 3.00 for the second straight season. There will always be concerns about drafting a closer on a poor team, but the only reason that’s a real concern is that stinky teams often have rubbish closers. Soria is a special pitcher who demonstrates his dominance whenever he gets the ball.

Mariano Rivera, NYY – Rivera didn’t post elite closer metrics in 2010, and his overall numbers, while decent, were buoyed by a 3.6% HR/FB rate and .222 BABIP – the third lowest of his career. Because he was relatively lucky when it came to keeping the ball in the park and getting a few more fly ball outs than normal, Rivera’s 1.80 ERA and 0.83 WHIP look a little better than they actually were. Most surprisingly, “Old Man” Rivera struggled to get batters out via the strikeout – and hitters made more contact with his darting cutter outside the zone (75.7%) than at any time in his storied career. He also threw fewer first strikes. Still – the 6.75 K/9 rate was in line with his modus operandi from 1998-2000, when he only whiffed about 6.38 hitters per 9 innings. I’m a little worried about last year’s 3.65 xFIP, but not enough to drop him out of the top tier.

 
Tier 2 ($15-19)

Neftali Feliz, TEX – Since Feliz is still being considered for a spot in the starting rotation, I’m wary of putting him in the top tier. While his overall fantasy value will improve if that’s the case, it’s always dangerous to mess with a guy’s head in Spring Training when it comes to the bullpen/rotation arm-lengthening process, especially when a pitcher is briefly considered then thrust right back into the closing role. There’s no denying his effectiveness; only Matt Thornton had a better fastball (20.3 >19.3) among relievers in 2010 – when Feliz posted 40 saves, a 2.73 ERA, 0.88 WHIP, 9.22 K/9 and 3.94 K/BB. There’s a chance Feliz will get beat up a bit more this season, as he’s been remarkably lucky with regard to balls in play; his 2009 BABIP was .169 and last season, the figure was a still-low .224. I’m anticipating that number to trend closer to .275, and the ERA to bump over 3.00 this season. He’ll still get a lot of Ks and saves, but if pitching in Arlington half the time hasn’t caught up to the youngster yet, it promises to in the near future.

Jonathan Papelbon, BOS – Jonny Pap’s 2010 season was a disappointment; his 3.90 ERA and 1.27 WHIP were largely a result of an increased walk rate (3.76 BB/9 compared to his career rate of 2.59) and a HR/FB rate (9.1%) a few clicks above normal. In the past, Papelbon did an excellent job with runners on base, but his career LOB rate of 81.6% looks brilliant considering he only stranded 68.7% of base runners in 2010. With Daniel Bard beating down his door and Bobby Jenks in town to close games if needed, Papelbon will be on a short leash and could help yield a quality starter as the Sox approach the trading deadline. The good thing is that he’ll probably close out games wherever he ends up going, so he won’t lose too much value, but I can’t consider him an elite closer until he stops walking so many dudes.

Andrew Bailey, OAK – The 2009 AL Rookie of the Year dealt with an oblique strain last year and had a clean-up surgery on his elbow in September. The early word is that he’s approaching 100 percent and about 10 to 12 pounds lighter than last year after seeing some extra chunk on his frame in wedding photos. Along with the extra poundage, Bailey must have been toting around a horseshoe last season; despite a 3.80 xFIP and relatively low (7.71) K/9 rate, he posted a 1.47 ERA, albeit with just 25 saves in 49 innings. Despite the injury issues and one glaring red flag (.225 career BABIP), I’m still bullish on Bailey’s prospects this season because he’s got excellent command of his three pitches – a four-seam, mid-90s fastball, an effective curveball, and a solid cutter that treads about 89-92.

 
Tier 3 ($12-15)

Joe Nathan, MIN – Nathan is back from Tommy John surgery and looks good; he pitched a scoreless inning in his spring debut and said he felt fine. His fastball was running about 86-90 mph, only a few clicks below where it was in 2009 (93-94) before the elbow injury. While he’ll be the closer barring any setbacks, nobody’s expecting an immediate return to the dominant form he showed from 2004-09 with the Twins. Where he’ll go on draft day is anybody’s guess, but you shouldn’t have to reach for him before the fifth or sixth round in most formats.

Jose Valverde, DET – A strange thing happened to Valverde last season: he induced ground balls at an alarmingly high rate (54.7%), and his GB/FB ratio (1.69) was nearly twice that of his 2009 ratio (0.88). Whether this is a case of an old dog learning new tricks, or just a statistical anomaly will probably be settled this season, but career-highs for overall contact rate (74.7%) as well as zone contact rate (86.8%) indicate the veteran reliever is making a significant effort to pitch to contact. The .231 BABIP portends somewhat of a regression from last season’s 3.00 ERA, but since his career figure is just .265, it’s not a huge problem.

Matt Thornton, CHW – I really like what I’m seeing from Matt Thornton’s metrics: a gradually improving K/9 rate, acceptable BABIP levels, and ERA/FIP/xFIP lines under 3.00 (in every circumstance) for the past three seasons. As I mentioned before, his fastball is the best among major league relievers (20.3 in 2010), and he throws it almost exclusively (90.1%). Being a one-pitch closer doesn’t work for everybody, but when your fastball is as good as Thornton’s, it’s okay to forget the curveball… and give ‘em the heater!!!

Chris Perez, CLE – The man who was developed as the Cardinals’ “closer-of-the-future” became the man for the Tribe when he was dealt in June 2009 and Kerry Wood got injured in Spring Training last season. He got the job done in 2010, but there are some reasons to be cautious heading into another full season. First, his 1.71 ERA belied some sinister figures, including an xFIP of 4.30 and .222 BABIP. His HR/FB rate was also unsustainably low at 5.5%, which means that some of those line drives and fly balls are bound to find gaps and escape the yard in 2011. He’ll probably cost you a pretty penny based on last years numbers, so don’t be too freaked out if you miss out on him and end up with a few of the more save-challenged but no more uncertain bargains in the next tier.

 
Tier 4 ($8-11)

Daniel Bard, BOS – I thought the Bosox would have dealt Papelbon last season before the trading deadline, but he’s still the closer. That leaves Bard, along with the guy that’s next in this tier, among the best two setup men in baseball, let alone the AL East. It just doesn’t get much better than Bard’s fastball/slider combo, and it’s a safe bet that his K/9 rate will be over 10.0 again this season.

Rafael Soriano, NYY – I have a feeling that Soriano will be tough to acquire in many drafts, but if folks over think the fact that he’s no longer a closer, you might be able to get him for a song. With talent like this, the Yankees will be using him frequently to give Rivera some extra time off, and I wouldn’t be surprised if he gets a few two-inning saves after some late Yankee scoring counterfeits the necessity of Rivera.

Brandon League, SEA – With David Aardsma just getting off crutches, League will be the front runner to close out games for the Mariners. With his velocity, you’d expect League to miss more bats, but the secret to his success lies in getting mostly ground balls (career 3.09 GB/FB rate). If he can raise his K/9 a bit, he could hold onto the job for a while.

Frank Francisco, TOR – He’s the closer for the Blue Jays, and he’s still capable of striking guys out. Francisco has some competition if he struggles, namely Octavio Dotel and Jon Rauch, but his blown saves over the past few years have largely been due to bad luck; his ERA/FIP/xFIP have all remained under 4.00 since 2007.

David Aardsma, SEA – Nobody knows for sure when Aardsma will begin throwing after receiving hip surgery this December, but he could battle for the closer’s job once he comes off the DL in 2011. He wasn’t as spectacular in 2010 as his ’09 breakout, but his status is worth watching, as most expect him to be back at some point after April and before the All-Star break.

Fernando Rodney, LAA – Despite a career WHIP of 1.44, Rodney continues to get opportunities to close games, but if he can’t cut down on his walk rate, his days working the ninth are numbered. An additional concern is that Rodney’s K/9 rate is declining. Scott Downs offers a better option than Rodney.

Matt Capps, MIN – Capps doesn’t get a lot of strikeouts (career 6.97 K/9), but last season he induced more ground balls and pitched more effectively with runners on base. He’ll be the Twins eighth-inning guy unless there’s a problem with Nathan.

Kevin Gregg, BAL – Gregg has jumped around a lot since 2006, and he’s now pitching for his fifth team in six seasons. There’s nothing in his career numbers to indicate he can be elite, and since 2007 when he became a closer for the Marlins, he’s racked up 26 blown saves. I’d prefer the battle to be between strike-out heavy lefty Mike Gonzalez and Koji Uehara, but there’s no word on whether or not Buck Showalter understands sabermetrics.

 
Tier 5 ($3-7)

Kyle Farnsworth, TB – It looks like Joe Maddon is leaning toward a closer-by-committee situation, which might be the best approach considering Tampa’s list of shaky bullpen options. A whopping seven of the eight pitchers who worked the bulk of relief innings for the Rays are gone, and while team officials claim to be pleased with the likes of Farnsworth, Joel Peralta and Adam Russell, there’s still a lot of question marks. Farnsworth is the closest they have to a proven closer, but lefty Jake McGee will probably inherit the job at some point.

Koji Uehara, BAL – Uehara was scratched from his scheduled appearance Thursday after receiving a cortisone shot in his elbow and seems to have lost his lead on the closer battle. He’s struggled through injuries the past couple years but was incredibly effective last season out of the bullpen (11.25 K/9, 11.0 K/BB, 0.95 WHIP, 2.86 ERA, 2.91 xFIP).

Chris Sale, CHW – Kenny Williams and Ozzie Guillen might want to consult with Brian Cashman on how to deal with Sale, as they’ve already started pondering some Joba-like questions regarding his use in the bullpen or as a starter. For now, he’ll be in the bullpen competing with Thornton for the closing job. Expect about a strikeout per inning and a solid ERA, but don’t plan on any saves unless Thornton implodes.

Jake McGee, TB – McGee is worth watching as the season approaches, but don’t spend too much money on him. He’s largely untested and hasn’t been named the closer.

Joaquin Benoit, DET – He was unhittable last season pitching for the Rays, and the Tigers have invested a lot in his future in Detroit. If Valverde encounters any trouble, he’ll be the first they turn to.

Scott Downs, LAA – Downs should get first crack at the Angels’ closer job if (when?) something goes wrong with the volatile Fernando Rodney. It’s either him or Kevin Jepsen. Stay tuned.

Brian Fuentes, OAK – Andrew Bailey isn’t the healthiest guy in the world, and Fuentes has a lot of experience as a closer. If you’re grabbing Bailey, Fuentes makes sense as a handcuff.

Octavio Dotel, TOR – Dotel’s still got bat-missing ability and could get the nod in the ninth should Francisco and/or Rauch not work out. He’ll give up a few more homers this season, but he’s easily worth a couple bucks in auction leagues.