Thursday's big Cleveland-San Diego swap may have been known as "the Brad Hand trade," because he's a two-time All-Star. Depending on how things play out in the future, it might be the "Francisco Mejia trade," because he's a consensus top prospect. Almost no one thinks of it as "the Adam Cimber trade," because most fans probably had absolutely no idea who Cimber even was before Thursday.
Here's the thing, though: Cimber is really good. He doesn't pick up wins or saves, but he's got a 51/10 strikeout/walk ratio and a 3.17 ERA as a rookie, and he's someone the Indians valued highly. This is going to happen a lot over the next 10 days. In a trade market likely without an elite starter available, in a baseball world where bullpens are taking over, relievers are going to be the deadline's most valuable currency.
Here's the thing about good relievers, however: You don't know all of them. Sure, you know the big closer names like Zach Britton, Fernando Rodney or Jeurys Familia. But there are so many good relatively anonymous relievers working in non-closing situations who don't pile up wins or saves. These are the guys who, when traded, will cause fans to ask: Who? Why is this guy any good?
They deserve better than that. So do you. Let's help you understand who the actual best relievers who may be available this year are, and what makes them so useful.
Thomas Pressly, Twins
What makes him good: his velocity, and his spin

It's been nearly six years since the Twins took Pressly from the Red Sox in the 2012 Rule 5 Draft, and for most of that time, you've had absolutely no idea that he's been kicking around Minnesota's bullpen. He's had nice ERA marks -- 2.86 in 2014, 2.93 in '15 -- but despite impressive physical tools, the underlying numbers just weren't interesting. In '14, of 262 relievers who threw 20 innings, Pressly's 11.5 percent strikeout rate was sixth-worst.
You might say Pressly has been working toward something: This year, his 34 percent whiff rate is 18th of 229 relievers who have 20 innings.

Pressly has always had the physical tools, really, but we're able to express them a little better now. Of 379 pitchers who have thrown 100 four-seams this year, his spin rate is seventh. Of 159 pitchers with 100 curves thrown, Pressly's spin rate is second, and first of active pitchers, since Garrett Richards is injured. And of 269 pitchers with 100 sliders thrown, he's fourth in velocity, behind a trio of Mets. It's easy to see progressive teams that value such things, like the Dodgers or Astros, being extremely interested here.
Adam Conley, Marlins
What makes him good: his added velocity

The Conley story looks a lot like the Andrew Miller and Hand stories: Mediocre lefty Marlins starter becomes dominant relief weapon and ends up with Cleveland. The Indians probably won't go get Conley, too, but there's a lot of similarities here, because after spending three relatively unremarkable years in Miami's rotation (4.60 ERA in 62 games), he moved to the bullpen this year.
You might say it's gone well. Conley's ERA is down to 2.88, but more importantly, his strikeout rate has nearly doubled from a below-average 16 percent to a fantastic 31 percent, a top-35 mark. Lefties have hit just .125/.222/.270 against him, and he's allowed more than one run just once all year.
There's more than one reason for that, but none stands out more than pure, simple heat. Last year, as a starter, Conley's four-seamer averaged 89.7 mph. This year, it's up 94.9 mph. It's the largest velocity increase of any pitcher in the game. Velocity isn't everything, but it's hard to get past that jump.

Kirby Yates, Padres
What makes him good: his new splitter

Yates kicked around four teams in four years, putting up a 4.78 ERA between 2014-17 for the Rays, Yankees, Angels and Padres, with a brief stop with Cleveland during the offseason of 2015. He got into one game with the Halos last April before being designated for assignment; when he landed with San Diego, he was quietly outstanding. Yates' 38.1 percent strikeout rate was the seventh-best in baseball.
Despite the whiffs, Yates still had a problem -- he gave up too many fly balls and too many home runs. So this year, he took the new splitter he'd thrown 11 percent of the time last year and threw it three times as often, 34 percent. Yates has barely used his slider at all. The result is an enormous jump in ground ball rate, from 29 percent last year to 50 percent this year. It's the largest grounder jump in baseball.
Going to the Padres, Yates said earlier this year, was "a match made in heaven. It's the best thing that's ever happened to me for my career."
"When I got here," he continued, "it was, 'We like your split, we want you to throw it more.'"
It's worked out well for San Diego. Soon, it may work out well for a contender, too.
Richard Parker, Angels
What makes him good: his velocity, and his splitter

Parker had his moments as a middle reliever for the 2013 Cubs (2.72 ERA), but a poor '14 (5.14) led to a '15 mostly out of baseball. From there, it was a whirlwind; he signed a Minor League deal with Seattle in December 2015, then was passed around on waivers, going from the Mariners to the Yankees to the Angels to the Brewers back to the Halos all before the end of '16.
In 2017 with the Angels, Parker was pretty good, putting up a 2.54 ERA while striking out 86 in 67 1/3 innings. This year, it's been more of the same, a 3.05 ERA with 50 strikeouts in 44 1/3 innings. Among relievers with 100 innings in the past two years, he's 15th in ERA, and 10th in strikeout rate. Where did that come from? It starts with a split-finger that he barely used until Parker got to Anaheim, and now makes up a third of his pitches.

"It's something I messed around with and ended up really liking it," Parker said earlier this year. "I started using it, and then last year, the confidence [catcher Martin Maldonado] gave me with that pitch was a big contributor in the success that I had."
Parker allowed just a .156/.145/.284 against the splitter last year and a .109/.132/.200 mark against this year. If you care about saves, well, he's got a few, but he wouldn't likely be a closer for a contender. Parker would be a dangerous setup man who can miss bats.
Kyle Barraclough, Marlins
What makes him good: the fact you can't hit him

Barraclough -- pronounced "bear claw" -- has actually been traded in a Deadline deal once before, going from St. Louis to Miami three years ago as the prospect return for Steve Cishek. In addition to teammates Conley, Brad Ziegler and Drew Steckenrider, Barraclough is one of a handful of interesting Marlins relievers, one who has already appeared in trade rumors.
In his case, however, that 1.28 ERA is a little misleading, because an uncomfortably high walk rate -- over five per nine for his career -- doesn't actually back up that level of run prevention. That said, Barraclough is incredibly difficult to hit; he actually just went through a two-month stretch in May and June where he got into 24 games and allowed just three hits along with one run. That helps put him near the top of an insane list.
Lowest batting average against by relievers with a minimum of 100 batters faced in 2018
.122 -- Josh Hader
.126 -- Barraclough
.126 -- Albertin Chapman
.134 -- Sean Doolittle
Barraclough has got that, plus an above-average 28 percent strikeout rate. (He also can't be a free agent until after 2021.) All of a sudden, you understand why so many contending teams are interested. He's got zero wins and most fans don't know his name, but that simply doesn't matter anymore. Pitchers who miss bats and don't allow hits are always in demand.