CLEVELAND, Ohio -- They prefer to be known by a nickname not necessarily endorsed by their family friendly, law-abiding organization.

But their bosses don't raise a public complaint because, in a results-oriented business, these guys get results.

They are "The Bullpen Mafia," a group of relievers that typically comprises most, if not all, of the Cleveland Indians' bullpen. Its specialty: eliminating opposing hitters.

Without the bullpen, the Indians likely would be staring at a third straight season of 90-plus losses. Instead, the Tribe is 47-42, a half-game out of first in the American League Central Division as the "second half" begins Thursday.

Tribe relievers are 15-9 with a 3.18 ERA and 22 saves in 28 chances. They have given up 92 earned runs in 260 1/3 innings and struck out 212. The bullpen is tied for second in the American League in victories and is third in ERA and fifth in innings.

Beyond the near-guarantee of success on most nights, the group is cloaked in ambiguity and mystery. It likes to keep outsiders guessing.

"Like the real Mafia, the makings are kind of convoluted and, uh, cloudy," closer Chris Perez said. "There are legends and tales, but nothing's been confirmed."

In a pre-batting practice clubhouse card game last week, recognized charter members Joe Smith and Tony Sipp decided to play it coy. Because they could.

Asked about The Bullpen Mafia, Smith said: "I don't know what you're talking about."

Laughter.

"No, really," Smith said, "I don't."

Sipp effectively zipped his lip, too.

"Oh, no," he said. "You're not going to get any information out of me."

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Later, when pressed near his locker, Smith cracked a smile and filled in some blanks. He is virtually certain the nickname came from a fan via Twitter; the relievers immediately liked it and ran with it -- as far as they could, given the violent connotation.

Officially licensed merchandise is on hold.

The Bullpen Mafia holds out hope on account of precedent. The Yankees had "Murderers' Row." The Astros had "The Killer B's." Royals reliever Joakim Soria is nicknamed "The Mexicutioner." So why can't the 2011 Tribe bullpen have its slice of the pie? All in fun, of course.

Perhaps telling, perhaps not, the relievers have not held any formal meetings. As a result, no ironclad criteria has been established for inclusion. Smith said they are going with the following, subject to change:

• Must have faced a decent number of hitters. At this point in the season, it is roughly 125.

• Must have worked in at least a few high-leverage situations and gotten more than one important out.

• Must at least feign an interest in Twitter.

• Must be willing to hang out together periodically off the field.

"Twitter is an important part of this whole thing, which I think makes us unique," Smith said. "If you don't tweet, or try to tweet, we've got issues with you."

Twitter, more than other outside mechanisms, has fueled the popularity of The Bullpen Mafia. The relievers don't have enough hours in the day to read all the pertinent tweets.

"It's funny to see this whole thing create its own legs and start walking," veteran right-hander Chad Durbin said.

Lack of interest in Twitter and socializing have put veteran lefty Rafael Perez on the bubble -- at least according to Chris Perez.

"Raffy doesn't conform to any of our mob practices," Chris Perez said. "He's got a Twitter account, but I don't think he's tweeted yet. Even we don't know what he's up to or where he is. We're not sure if he wants to be a member."

Smith respectfully disagreed.

"He's in," Smith said of the wiry left-hander. "It's just taken him a little longer to come around."

Any reliever who suits up for the Tribe this year is free to apply for membership. It does not mean he will make the cut. Justin Germano and Josh Judy are two examples to date; neither pitched enough or lasted long enough.

In Germano's case, he was gone (designated May 19) before the concept really took hold.

"Those who don't get in know it's nothing personal," Chris Perez said. "Just business."

The rank-and-file have decided that the closer, no matter who it is, fills the role of "don," if you will. Chris Perez willingly accepts the responsibility.

"I'm not afraid to delegate, though," he said.

At present, all seven members of the bullpen are confirmed to be in The Bullpen Mafia. No members are on the disabled list or in the minors.

Here is a capsule look, in alphabetical order:

Chad Durbin, RHP

How acquired: Free agent, March 1.

Role: Short man. Can go long if necessary.

Also known as: The Durbinator.

Season stats: 34G, 2-1, 6.51 ERA. Has allowed just three of 22 inherited runners to score -- tied for fifth-best efficiency in AL.

Skinny: Soft-spoken, savvy veteran. Member of two World Series teams with Phillies. Also pitched for Tribe in 2003 and 2004.

Frank Herrmann, RHP

How acquired: Minor-league non-drafted free agent, August 2005.

Role: Long man.

Aka: The Herrmannator; The Professor; Herrmannmeistermeisterburger.

Season stats: 19 G, 1-0, 3.90 ERA. Has allowed one earned run in his last 16 innings.

Skinny: The brains of the operation, Herrmann graduated from Harvard with a degree in economics. His money pitch, a four-seam fastball, has its own nickname: "Harvard Heater." Multisport schoolboy legend in New Jersey, or so he says. Verified to have scored 1,000-plus points for Montclair Kimberley Academy varsity hoops. Carries silver briefcase entrusted to him by former Indian Kerry Wood.

Chris Perez, RHP

How acquired: Trade from Cardinals, June 2009.

Role: Closer.

Aka: Pure Rage; C.P.

Season stats: 36G, 2-4, 2.43 ERA, 21 saves. Has converted 21 of 22 save opportunities this season, 31 of 32 dating to last season. Has, however, given up game-winning homers in two of his last three non-save situations. Among relievers who qualify, ranks 16th in the AL in ERA.

Skinny: Likes crossword puzzles. Diligently signs baseball cards out of envelopes for fans. Readily available to reporters. Known for his facial hair.

Rafael Perez, LHP

How acquired: Non-drafted free agent, January 2002.

Role: Matchup lefty. Can face multiple hitters.

Aka: Raffy Coolo.

Season stats: 40G, 3-1, 1.91 ERA. Didn't allow an earned run in first 12 1/3 innings this year. Hasn't allowed a home run and his WHIP of 1.195 is his best since 2008.

Skinny: Quieter than quiet. Likes to keep to himself. Reasonably tight with starter Fausto Carmona.

Vinnie Pestano, RHP

How acquired: 20th round, 2006.

Role: Setup man.

Aka: The Pistol; My Cousin Vinnie.

Season stats: 37G, 1-0, 2.97 ERA, 1 save, 33.1 IP, 47 K. Indians are 26-11 when he appears. Ranks tied for seventh in AL with 12 holds. Has at least one strikeout in 29 appearances. Owns only save not belonging to Chris Perez.

Skinny: Shy. Needs to be coaxed out of shell. Comedic when he wants to be. Carries pink backpack as part of rookie "hazing." Not satisfied with any of his nicknames to date.

Tony Sipp, LHP

How acquired: 45th round, 2004.

Role: Setup man.

Aka: Tony Sipprano; T-Sipp, Sippy Cup.

Season stats: 40G, 4-1, 2.72 ERA. Ranks among AL leaders with 17 holds. Has given up three earned runs in last 16 appearances. Strikeout to walk ratio of 2.43-1 is the best of his big-league career. Has the fifth-highest number of appearances of any AL pitcher so far this season.

Skinny: Introspective. Constantly on the computer listening to music or studying something. Likes to play cards.

Joe Smith, RHP

How acquired: Trade from Mets, December 2008.

Role: Matchup righty.

Aka: Smitty.

Season stats: 34G, 2-1, 0.85 ERA. Has not given up an earned run in his last 25 appearances -- longest active streak in majors, second-longest streak overall. Leads AL relievers in ERA.

Skinny: Constantly on his handheld device. Unofficial traffic cop of clubhouse. Having dealt with the New York media, he is keenly aware of reporters' methods. Former Horizon League pitcher of the year (Wright State). Quality basketball player.

On Twitter: @dmansworldpd