MILWAUKEE -- Josh Hader kind of looks like a renegade. His musical taste is renegade-like. He pitches like a renegade, with a style as distinctive as it is effective. Hader might even want people to think he's a renegade, except he has anything but a renegade personality.

"Hi, I'm Josh," Hader says to those he meets, reaching out with a friendly hand. It's a courtesy he extends even to sportswriters, who are not really accustomed to being welcomed in that way, at least not in the clubhouse. It's not exactly renegade behavior. No, the renegade part of Hader's persona doesn't emerge until he unleashes the ball toward home plate. Then, as he likes to say, he's ready to eat.

Hader is feasting so far this season. Opposing batters are hitting .068 against him -- 55 points below the big league average for pitchers. Lefty hitters are 1-for-23; righties have fared only a little less horribly, going 4-for-50. The only sign that Hader is human is that he's given up two home runs -- Tommy Pham and Starling Marte have both touched him up, both righties. So far in his big league career, Hader has yet to serve up a home run ball to a lefty hitter.

Hader is neither a closer nor a starter, though he can do both. The Brewers lefty is a member of that re-emergent species of in-between hurlers that is helping redefine the way we think about pitching staff construction. This season, there are 92 relievers averaging more than three outs per appearance. Five years ago, there were just 42. With that combination of dominance and exposure, Hader is on pace to rack up 5.4 WAR this season, more than any other relief pitcher and more than all but 13 starting pitchers. According to FanGraphs it would be the highest total we've seen from a relief pitcher. Ever. That's why suddenly everybody is scrambling to write about young Mr. Hader. Editor's Picks Why a 21-K game is MLB's best record that can actually happen

As first dose of Mets drama hits, will Mickey Callaway's plan work?

Whose hot starts will turn into breakout seasons? 2 Related

"Look, I don't know that you ever predict the level of dominance that Josh has displayed," Brewers GM David Stearns said. "Even over a short period, that's pretty extraordinary. That's why all of these articles are being written about him, because what he's doing we haven't seen that much. And when we have seen it, it's been big names like [Aroldis] Chapman, and Randy Johnson, guys who have earned their stripes in the big leagues as dominant pitchers for a long period of time."

The lofty value metrics Hader is posting almost obscure his eye-popping underlying statistics. He is striking out 18.8 batters per nine innings, which would break the record set by Chapman in 2014 by more than a full K per nine. He's whiffed 61 percent of opposing batters and is striking out eight hitters for every walk. A FanGraphs-favored measure of pitcher dominance is strikeout percentage minus walk percentage. Hader's dominance number is 53.2 percent. That, too, would obliterate the existing record -- Craig Kimbrel's 44.2 percent in 2012. All of this is coming from a young pitcher who went through his minor league career thinking he was destined to become a big league starter.

"A big key to Josh is that he's open to what's best for the team," Stearns said. "He came up here and adapted to that [middle relief] role very well, and he enjoys that role. If tomorrow we asked him to go back to starter, he'd do that and enjoy that role. He's a guy who really will take to any task."

Hader looks as much like an extra from "Dazed and Confused" as anything else. When you think of an intimidating closer, you think of an intense demeanor. Jonathan Papelbon staring down the hitter beneath the bill of his cap. Rob Dibble's controlled wildness. Al Hrabosky firing the ball into his glove. Exaggerated facial hair configurations. The sizzle of a Chapman fastball. Hader, who reaches 98 mph with his own heater, has a narrow frame and long, skinny arms. He has a broom of sandy-blond hair flopping around under his hat and a sleeve of tattoos on his right arm. Last year, he wore spectacles on the mound but this year switched to contact lenses. These things give him a distinctive countenance, but not one you'd label as intimidating. That is until the ball leaves his hand.

As good as Hader was as a rookie, it's still shocking to see what he's doing in just about every outing. His singular choice of walk-in music -- "Renegade" by Styx, a long-haired '70s band straight out of the heyday of the vinyl era -- is becoming the new sound of dread for Milwaukee opponents. At this time a year ago, Hader was still a starting pitcher. He has embraced relief pitching in a way few top prospects do so early in a career, even switching to pitching exclusively from the stretch. That has paid off in the form of a more consistent delivery.

"This year, being taken out of the wind-up and going strictly from the stretch, being able to master that timing throughout my delivery," Hader said, "it's definitely helped me have a more consistent release point every time. Being able to go through my throwing program working from the stretch, I think that's really been the biggest thing to help me stay consistent."

Hader was on the prospect radar for years, even as he switched organizations from Baltimore to Houston to Milwaukee. He was developed as a starter and rated as the Brewers' top pitching prospect when he was called up to the majors for the first time last season to help with Milwaukee's playoff push. He helped plenty, posting a 2.08 ERA out of the bullpen with 68 strikeouts in 47⅔ innings, though he didn't attract even a single down-ballot vote in the National League Rookie of the Year balloting.

In other words, Hader was supposed to be good, and as a rookie, he did not disappoint. Still, no one foresaw the fury he's unleashed upon the baseball world in 2018. As Stearns said, there is really no way to know a player is going to ascend to this kind of dominance. We only know it when it happens, and for those who must absorb the drubbing -- the hitters -- it's already too late.

"He's really deceptive," teammate Christian Yelich said. When Yelich was with the Marlins last season, he faced Hader twice. He struck out both times. "He creates a really good angle for left-on-left [matchups]. And obviously he has really good stuff. When somebody has that combination, it's always tough. He has a really good stride so the ball gets on you. You don't face a lot of guys like that, and it's a really tough at-bat. It's good to have him on our side."

Hader's stuff would play no matter what, but he augments it with a three-quarters arm slot that makes it challenging for lefty hitters to get a read on his pitches, a cross-body delivery that hides the ball against righties just long enough, and little hesitation as he goes into a motion that messes with batters' timing. All of this, combined with his raw stuff, explains why Hader's platoon split is virtually nil. But Hader had to develop these traits as a professional. He wasn't drafted by Baltimore until the 19th round of the 2012 draft, underscoring just how far he's come. He threw in the 80s when he was in high school before his fastball leaped into the 90s soon after he turned pro.

"[My delivery] has always been similar, even coming through the minor leagues, with little tweaks to make sure the mechanics are flowing," Hader said. "There were times in my career where I really had to learn to pitch inside to righties. Obviously with my closed stance, I'm not going towards them. I'm kind of going away from them, and I've really got to get my arm over there to make sure it's staying inside. If I don't get it over there, then it's mostly over the middle."

Josh Hader may never nail down the "intimidating facial hair" part of a relief ace's job, but he doesn't need to. Tony Quinn/Icon Sportswire

Hader changed organizations twice despite drawing frequent comparisons to Red Sox star Chris Sale. The fastball was Hader's bread-and-butter during much of his developmental phase, almost too much so -- for years, Hader profiled as a pitcher with good stuff but only one plus pitch. That is certainly no longer the case, as his slider has developed into one of the game's best.

"This didn't happen by accident," Stearns said. "Josh worked really hard. He was labeled at times as a one-pitch pitcher. And even though it was a really good pitch, he was determined to make himself into more than a one-pitch pitcher, and he's done that. He's throwing strikes, keeping hitters off balance and proven to be a real weapon out of our bullpen."

You can see Hader's emergence as more than a one-pitch guy by burrowing into StatCast pitch data from baseballsavant.com. Since the beginning of the 2017 season, only two pitchers have a lower overall expected WOBA than Hader -- Sean Doolittle and Pat Neshek. When you look at specific pitches, you find Hader ranks 11th with his fastball and third with his slider. With two elite pitches, he has all but abandoned the changeup he used to mix in. When you combine that with the more consistent command, the bottom-line effect has been devastating.

"The way he throws across his body, his delivery is kind of a funky, unique delivery," Yelich said. "When you've got his stuff, you just know it's going to be a tough matchup. Even if I had never faced him before, I would just know he's tough from video because of the way he delivers the ball and because his mechanics are so unique."

Nowhere was Hader's level of devastation more evident than at Cincinnati on April 30. That night, the Brewers had grabbed a 6-5 lead with a three-run seventh, capped by Domingo Santana's two-run double. After Brandon Woodruff recorded the first out of the bottom of the seventh, Hader was summoned to face Reds star Joey Votto. He struck him out on three pitches, setting the tone for a historic night.

Hader went on to face nine batters, striking out eight of them, and became the first reliever to ever record a save of less than three innings with eight strikeouts. He threw only 37 pitches. According to Elias, Hader became the first pitcher to record at least eight outs in a game, all via strikeout, since the mound was moved to its current distance in 1893.

"I don't know what to say about Josh. Literally," Brewers manager Craig Counsell told reporters after that outing. "Your mouth's kind of wide open watching it. It was absolutely incredible."

Meanwhile, Hader simply said, "Fun. A lot of fun."

Fun isn't probably the word Votto & Co. would have chosen to describe the evening. However, for Milwaukee, the early-season dominance from Hader has sparked an overall bullpen performance that has propped up the Brewers through offensive struggles and a spate of key injuries.

"We've had a bunch of guys that have pitched well, as much as anything," Counsell said. "That's what has allowed this to work. They've all done such a nice job."

Despite missing closer Corey Knebel for most of the first six weeks of the season, the Hader-led bullpen ranks fourth in the majors by bullpen WAR, per baseball-reference.com, and second in win probability added, per FanGraphs. Now that Knebel has returned to the mix, Milwaukee's bullpen might be the best in the National League.

"The entire bullpen has been outstanding, really for the entire season and especially since Corey went down," Stearns said. "Josh gets the headlines, and deservedly so for what he's accomplished, but one through seven or eight, whoever we've had out there has gotten the job done. And they've gotten the job done in very challenging situations." The Shohei Ohtani experience Keep track of the Japanese phenom's bid for greatness on both sides of the ball. Story »

When you have a weapon as potent as Hader, the pleasant problem then becomes the best way to leverage him. Starter? Closer? Dominant seventh- or eighth-inning guy? That's generally been the choice over the past 30 years for young pitchers developed as starters who see their stuff play up in relief roles. But the calculus has changed over the past few seasons, best exemplified by the rise of Cleveland's Andrew Miller as a dominant multi-inning killer. After Miller's 2016 postseason, everybody wanted a Miller of their own. But the comparison to Hader wavers in this respect: Miller had long since washed out as a starter. You can't say that about Hader -- he's never started a big league game. And given the way the industry is changing, he might never make that first start.

"It has definitely changed," Stearns said. "The industry's perception of the value of a reliever, and how we're deploying relievers, has changed. The value that Josh has provided us this year has surprised even me about the value any reliever can provide a club. But when you put guys in high-leverage situations and they are able to execute in those situations over multiple innings, it creates tremendous value. I don't know how many guys can do it, but when you have a guy who can and do it at the level that Josh has been, it's pretty important."

In his current role, Hader ranks second on the Brewers in fWAR, better than any member of the rotation. In terms of win probability added, he ranks fifth among all big league pitchers, though he's actually second in his own bullpen behind Jeremy Jeffress, whose WPA is bested only by Max Scherzer. These next-level ways of looking at pitcher roles have transmogrified not just the way hurlers are used, but increasingly how they are valued in the marketplace. For most of the past three decades, saves have been the meal ticket for relief pitchers. Now you get the sense that saves are not going to get you paid as much as the versatility to dominate in a whatever-the-game-calls-for kind of capacity. If Miller is healthy by the end of the season, we could see that play out this winter when he hits the open market.

All of this bodes well for Hader's future earnings, even if he never enters the Milwaukee rotation or becomes the guy who by default gets the ninth inning. He might prove too valuable for either path. And whereas so many young middle relievers will state an emphatic preference to either start ("I'm a starter" is the familiar refrain) or to close, Hader likes what he's doing just fine. And why wouldn't he, when he is striking fear into the hearts of batters all across the National League?

"I love the mentality of it," Hader said about his relief role. "You have to come in with your best stuff because you may only see one hitter. You really have to attack from the start. For me, it's all about letting it eat for however many outings I'm out there. Then going out and doing it again the next day."

There's a mystique to an attitude like that, just as there is a mystique to a 24-year-old whose walk-in music is a vestige of the disco era, a time when multi-inning relievers were the norm, though the firemen of those days were a lot more democratic when it came to keeping balls out of play. But you have to ask: In a time when almost all players, regardless of age, pick songs from the hip-hop, country or pop genres, how does such a young guy end up with a song like "Renegade" as his tune? What does that say about his personality?

"I like classic rock!" Hader said. "I'm a big classic rock guy. I was with a buddy, listening to music, while watching a game and that song came on. I was like 'This would be a sick walk-out.'"

Sick, indeed, and it's big league batters who are feeling nauseous when baseball's renegade emerges from the bullpen gate.