Relievers are the byproduct of deficient starters, much like second basemen are to shortstops, or left fielders are to center fielders, or reality television “stars” are to the failures of human development. However, inherent deficiency doesn’t preclude potential value, because let’s face it, somebody has to pitch in relief (and be good at it), and somebody has to slide over to second base, and somebody has to get paid for candid promiscuity and binge drinking for our amusement.

When it comes to ranking relievers, I wanted to step away from the established construct and craft specific tiers to compartmentalize such an abstract pool of talent. After all, every pitcher in the minors could be considered a reliever, depending on the evaluation linked to each player. For this exercise, I spent a week talking to scouts, asking them about current relievers, current starters that could become relievers, and failed position players that have become relievers. If a scout mentioned a potential relief future, I documented it. If a scout failed to mention a reliever, despite his sparkling numbers, or your admiration for his services, I didn’t force the name into the mix. This article would require 10 parts to properly detail every arm that could have an impact in relief. That wasn’t the goal.

The new tiers should be self-explanatory, and not meant to be read as a black-and-white ranking of the arms. As you will notice, I didn’t bother ranking the “best” present reliever, or the “best” future reliever, and I didn’t highlight the one arm I felt was overrated. Of all the articles I have written during my brief tenure at Baseball Prospectus, this article required the most research. After five days of intense communication with my scouting brethren, I present to you a page full of names in cute little tiers.

You Must Be At Least This ____ Tall to Pitch in Relief

Abnormally Large Humans Division
Jose Ceda (Marlins)
Requirements: 6-foot-4/275 pounds (kind)
TCF: Ceda has easy plus-plus fastball velocity, normally working in the 94-96 range, though he can touch higher. His fastball command is improving. His slider is effective, and his split/change looks even better, giving Ceda the necessary components to pitch in a late-innings role at the major-league level.

Billy Bullock (Braves)
Requirements: 6-foot-6/225 pounds
TCF: The 23-year-old righty has a plus fastball, delivered with good angle with some natural weight and run. His slider has a few plus grades attached to it, but isn’t consistent, with velocity ranging from the upper 70s to the mid-80s. His command is below average and limits the overall effectiveness of his above-average arsenal. Bullock will eventually get a look at the highest level because of his ability to miss bats. If the command takes a step forward, he could stick around in a late-inning capacity.

Brad Brach (Padres)
Requirements: 6-foot-6/210 pounds
TCF: Brach is a 25-year-old reliever with a mature arsenal and above-average command. He lacks elite stuff but uses his height well, creating a good angle on a 92-96 mph fastball. He can throw his slider and splitter for strikes, and uses pitch sequence as a weapon. Despite not having overpowering stuff, Brach is able to produce overpowering results, missing bats, limiting walks, and showing the necessary mentality to handle late-inning assignments.

Phillipe Aumont (Phillies)
Requirements: 6-foot-7/255 pounds
TCF: Aumont has been on the prospect rollercoaster since being selected 11th overall in the 2007 drafts. He reached the heights of top-100 prospect status as a starter, and fell to the depths of third-tier status by the end of the 2010 season. Aumont has since regained his footing, this time with a permanent move to the pen. He’s finding his command and looking like a legit candidate for late-inning work at the major-league level. At his best, Aumont brings a plus fastball, with low-90s velocity and bowling ball weight that is hard to lift. His four-seamer can find the mid-90s, and his curve can miss bats and is effective against both lefties and righties. A lack of command crushed Aumont in the rotation, but it has taken huge steps forward in the pen, helping his heavy arsenal become effective. If the command holds up, the stuff will make him a major leaguer.

Loek van Mil (Angels)
Requirements: 7-foot-1/220 pounds
TCF: It’s hard to make a legit case for van Mil becoming a viable option at the back of a major-league bullpen, but his size keeps the dream alive. van Mil’s money pitch is a vertiginous fastball that works in the mid-90s, but looks 100 mph because he releases the pitch seemingly inches away from the hitter. Because of his size, the 26-year-old has mechanical issues and suspect command, and it’s hard to see him putting that component together. His slider isn’t a bad pitch and plays well off the steep fastball, but the overall command just isn’t there. Shame. He would be the tallest player to ever reach the majors.

Smaller Humans Division
Chase Ruffin: (Tigers)
Requirements: 6-foot-0/185 pounds
TCF: A late-inning mentality is an understatement; this 22-year-old Texan might best be described as a little crazy. Armed with a plus fastball (92-95 mph) with excellent life, and a plus slider (which may be better than his heater), Ruffin has all the components to become a late-innings reliever at the major-league level. The command could be sharper, but the arsenal is deep, the feel for sequence and situation is there, and the necessary insanity to thrive in the pressure of the role is more than present.

Kelvin Herrera (Royals)
Requirements: 5-foot-10/165 pounds
TCF: Herrera was finally moved to the bullpen this season because of a history of arm injuries, and he has been awesome. Using a plus-plus mid-90s fastball (that can touch higher) with excellent late life, an effective slider, and a changeup, Herrera pounds the zone, missing bats while not issuing free passes. He could see the majors at some point in 2012.

Clayton Schrader (Baltimore)
Requirements: 6-foot-0/200 pounds
TCF: A 10th-round selection in the 2010 draft, Schrader has exploded in his first full season, reaching High-A in late May while maintaining a strikeouts-per-nine-innings ratio of over 15. The 21-year-old Texan has a plus fastball that can reach plus-plus velocity, and he uses a mid-80s plus-potential slider to carve up hitters. His command could be sharper, but the ability to miss bats and force weak contact make him an attractive candidate for an accelerated journey through the minors.

Say, Didn’t You Used to be a Position Player?
Rafael Dolis (Cubs)
Requirements: Originally signed as a shortstop in 2004
TCF: He’s a 23-year-old flamethrower currently throwing fire at Double-A. At present, the results aren’t indicative of his late-inning repertoire, but at his best, Dolis can sit in the upper 90s with his fastball and flash a sharp mid-80s slider.

Jorge De Leon (Astros)
Requirements: Originally signed as a shortstop in 2006
TCF: After making the switch to the mound in 2010, this 23-year-old Dominican looked to solidify his prospect status in 2011, taking his plus-plus fastball to a full-season league. Despite a limited arsenal, De Leon has been solid in the Sally, showing more feel for the mound than expected and missing bats with his fastball. He would also qualify for the “Smaller Humans Division,” thanks to his 6-foot-0, 175-pound frame.

Luis Vasquez (Dodgers)
Requirements: Originally signed as a shortstop in 2003
TCF: Vasquez has always been dogged by well below-average command, and the story hasn’t changed in 2011. The dream stems from Vasquez’s ability to work his fastball in the mid-90s, and touch as high as 100 mph. The 25-year-old Dominican could reach the majors on the strength of his fastball, but without some semblance of command, he will remain a late-inning dream.

Manuel Soliman (Twins)
Requirements: Originally signed as a third baseman in 2007
TCF: Currently a starter, this 21-year-old Dominican has been impressive in Low-A, showing the ability to miss bats in a full-season league. Expected to remain a starter (at least in the short term), Soliman has an arsenal that could really play-up if moved to the pen, thanks to a solid-average to plus fastball and a hard slider that is difficult for both lefties and righties to hit.

Matt West (Rangers)
Requirements: Originally drafted as a third baseman in the second round of the 2007 draft
TCF: More people remember West for his positive test for a banned substance (and subsequent 50-game suspension) than his performance at the plate. After four years of less-than-stellar results, the 22-year-old Texan was given the opportunity to convert to the mound, and after only one bullpen session, the Rangers knew they had something special. West has yet to pitch in a professional game (outside of extended spring training), but his arsenal could push him up prospect lists in short order. As a position player, I only had West’s arm graded in the 55/60 range at third base, but on the mound, West can push his fastball to the upper 90s, and works comfortably in the 95-97 mph range. His slider, a second plus pitch in the making, has sharp tilt in the mid-80s, and his overall feel for the mound looks natural and easy. Lots can go wrong when position players attempt to convert to the mound, and plus stuff is only part of the equation, but the Rangers might have found something in West.

Current Rotation Prospects that Could End Up Being Elite Relievers, but Aren’t Necessarily Destined for Relief, so Don’t Freak Out if they Appear on this List
Stetson Allie (Pirates)
TCF: Allie has the potential for two elite pitches, with an upper-90s fastball and a wipeout slider. It’s lazy to label him as a reliever before he can be developed as a starter, but the stuff and the closer’s mentality, plus the questions about his command projection and development of a third pitch create an environment (premature) for relief chatter. Allie could become a frontline late-innings reliever as a fallback option, but if the package comes together, he could pitch at the top of a rotation.

Casey Crosby (Tigers)
TCF: With a potent combination of well above-average stuff and an injury history that has already resulted in two lost seasons (’08, ’10), Crosby looks like a good candidate to take his talents to the pen. When healthy, the 22-year-old can show plus-plus fastball velocity from the left side, with an excellent burst down in the zone. His curveball also flashes plus, but his overall command is suspect, and the past issues with his elbow are a constant reminder that the next pitch could again shut him down for the season. Crosby is also an abnormally large human, standing 6-foot-5.

Yordana Ventura (Royals)
TCF: Ventura has an easy plus-plus fastball that has touched elite velocity in bursts. It’s so good you can dream of its potential out of the pen. His curveball shows promise, as does his changeup, but the command isn’t there yet. Only 20 years old, Ventura should be given time to develop as a starter; he has more value in that role. But once you start dreaming of a triple-digit fastball with a lighting-quick release, it makes you want to rush him through the minors in the back of a bullpen. Ventura is also a member of the “Smaller Humans Division,” standing 5-foot-11 and weighing a generous 150 pounds

Chris Withrow (Dodgers)
TCF: This 22-year-old Texanhas plus-plus stuff, but shaky command and a below-average changeup. The former first-round pick still has a chance to develop into a quality starter, but as one scout recently told me, “Withrow could be a monster out of the pen. The fastball is a major-league weapon, and the curve (with a little refinement) could be another plus offering. He could be nasty.” Not a bad fallback option.

Dellin Betances (Yankees)
TCF: Given his performance this season, it’s hard to imagine anything but a second/third starter ceiling for Betances, but a few scouts told me how drool-inducing a move to the pen would be. Armed with a steep fastball that sits in the plus range and routinely touches higher, the 23-year-old is very difficult to square up. His best offering is a hard curve that might be one of the best secondary pitches in the minors, a legit plus-plus pitch. The command isn’t particularly sharp, and the changeup is behind the other offerings, but a move to the pen isn’t a necessity at this stage. That said, there aren’t many arms who can boast Betances’ ceiling coming out of the pen, with what could be two 70-grade pitches delivered by an abnormally large human (6-foot-8, 260 pounds)

Maikel Cleto (Cardinals)
TCF: The 22-year-old Dominican has a big body and a big arm, but iffy command and iffy secondary offerings limit his upside in a rotation. Cleto can dial his fastball to the triple digits in bursts, hitting the upper 90s with some life on the pitch. Because of his suspect mechanics and inconsistent comps, it’s a safe bet to project Cleto to the pen. He has a future at the back of a major-league bullpen if his command is refined and his two breaking balls can flash plus more than fringe. He is almost qualified for the abnormally large human distinction.

Adys Portillo (Padres) *Deep Sleeper
TCF: Portillo is only 19 years old, but he already shows a potential 70-grade fastball. His command is shaky and the secondary pitches are inconsistent, but the arm has enough electricity to find a home in the back of the bullpen if rotation development falls short.

Also receiving votes: Brad Peacock (Nationals), Jarred Cosart (Phillies), Jeurys Familia (Mets), Erik Goeddel (Mets) Ethan Martin (Dodgers), Neil Ramirez (Rangers), Tanner Scheppers (Rangers), Joe Kelly (Cardinals)

Just Because We Are Already Relievers, Doesn’t Mean We Aren’t Good Prospects
Jake McGee (Rays)
TCF: This24-year-old has a plus fastball that can show well above-average velocity from the left side. I’m not a fan of his body or his mechanics, but he should become a solid arm in the back of a major-league bullpen.

Yonata Ortega (Diamondbacks)
TCF: This 24-year-old Dominican has a thick body and a fastball that has been up to 98 mph this season.

Addison Reed (White Sox)
TCF: Reed is a 22-year-old with a plus-plus fastball and a good feel for command. His arsenal includes a plus-potential slider with and a split/change that one scout said he liked better than the slider. At present, Reed relies heavily on the fastball to miss bats.

Bruce Rondon (Tigers)
TCF: He has a big body with plus-plus fastball velocity/movement and hard slider. Command is well below average, but the Venezuelan is only 20 years old.

Daniel Tillman (Angels)
TCF: Tillman is a 22-year-old with an easy plus fastball, showing velocity in the 92-95 range, with natural weight to pitch. His low-80s slider is a solid-average pitch that plays well off the fastball. His command is below average, but could move fast if it improves.  

Tommy Kahnle (Yankees)
TCF: Kahnle is a 21-year-old reliever with a stocky body and a stocky fastball that misses bats and limits hard contact. His command is an issue, but with a plus-plus fastball and a solid-average slider, he has a chance to one day find a home at the back of a major-league pen.

Heath Hembree (Giants)
TCF: A 22-year-old with plus-plus fastball velocity, Hembree also has a very promising hard slider and good command. At present, he is crushing the California League and is looking like an arm that is going to move quickly.

Chris Carpenter (Cubs)
TCF: This 25-year-old has serious command issues, but the fastball can touch triple-digits. He has late-inning potential if the mechanics find some consistency, and he’s an abnormally large human.

Jhan Martinez (Marlins)
TCF: This 22-year-old has well below-average command and a well above-average fastball. He could find a home in the late innings if the command is refined and the slider develops into a plus offering. His arm is crazy fast.

Arquimedes Caminero (Marlins)
TCF: I couldn’t exclude a name like Arquimedes Euclides Caminero. When healthy, the 24-year-old Dominican can sit in the upper 90s and touch 100. How ironic is it that Arquimedes lacks fluid mechanics? Anyone? I need a life.  

Thank you for reading

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I just realized Loek van Mil and Jose Altuve are in the same league now! I hope somebody puts that on YouTube. Of course, Altuve may be 5'13" by the time they play in August. Perhaps it's a moot point.
The other Beloit Snapper in the picture with Loek van Mil is 5 foot 3 Chris Cates.
Cleto's command looked terrible when pitching a few weeks ago for the cardinals but his fastball looked like it had some great movement.
I didn't think he belonged on this list. Despite his current struggles, Chapman has shown flashes of brilliance at the major league level, and I consider him a major leaguer, regardless of his current assignment.
Thanks for this ... more like it would be interesting!
Oh, and I meant to ask what "TCF" means???
"The case for:"
Arquimedes Caminero is almost as great a name as Arquimedez Pozo.
Anything on Marquis Fleming? K/9 over 12 at double-A, supposedly plus change-up
I didn't receive a report on him. He's putting up great numbers, and I think he's a player worth keeping an eye on. His arsenal isn't overpowering; the changeup receives plus grades, but the FB is considered fringe-average to average. You have to have a special secondary pitch and special command to pitch in a late-inning capacity without a quality fastball.
"I didn't receive a report on him."
Does not compute with this:
"His arsenal isn't overpowering; the changeup receives plus grades, but the FB is considered fringe-average to average."
I didn't receive a report on him when I was talking to scouts about this list. I'm aware of what he throws, and have received reports on him in the past. For this specific report, as I indicated in the intro, I asked scouts who was tickling their fancy at the present. I didn't receive anything on Fleming.
Thanks for the clarification. I didn't put those items together.
Ah, yeah, wasn't expecting a big-ceiling report. Just nice to see a Rays reliever not hit the AA wall like Ryan Reid, Matt Gorgen, and others
Ethan Martin was apparently moved to the pen this weekend - do you have any word on his stuff there, and if not, can you find out? pretty please ...
He hit 97 mph. I think he has a future in relief, given the fact that he has two pitches that can play at the major league level. He needs to find some command.
Hey Jason, any thoughts on Justin De Fratus of the Phillies? Love their Pharm!
Very nice arm. FB can show plus-plus velocity; slider is another quality major league offering. Should reach the majors this season. I love the Phillies farm as well.
Good stuff Jason...What do you think of Arodys Vizcaino? I know a lot of Braves watchers think he is destined for the the pen.
He could be special in the pen, but he is still so young, and the changeup has room to improve, so I'd keep developing him as a starter until his case for the pen becomes to great to ignore.
What is your opinion of Fautino de Los Santos?
Love the FB, obviously. When I started compiling data for this article, Faustino was at the major league level, so he wasn't in my notes. Big league arm strength, quality slider, plus-plus FB. He should develop into a good late-innings arm, most likely in a set-up role.
Thanks, Jason! Any thoughts on Dan Cortes?
Abnormally large human. I've seen his FB/CB combo make hitters look absolutely foolish, but he's been hittable this season. He still has back-of-the-pen stuff. He just needs to refine his command within the zone and refine his breaking ball(s).
This was just a really really fun read. I look forward to the rest of the series. Thanks Jason.