Gerrit Cole has been the best pitcher in baseball during the young 2018 season. Through six starts, the newest member of the Houston Astros rotation is averaging almost seven innings a start and has a 1.73 ERA and the lowest FIP (1.92) among qualified starters in the American League. Cole leads all starters in DRA, the more sophisticated ERA estimator from Baseball Prospectus, with a 1.30 mark. Unsurprisingly, both BP and FanGraphs rate Cole at around 1.8 wins above replacement, also tops among starting pitchers. Perhaps most impressively, Cole, whose strikeout numbers have never quite matched his stuff, is leading MLB in both strikeouts and K%.

While the 27-year-old Californian is pleased with his performance to date, he doesn’t want to dwell on it, preferring to focus on the more than 80 percent of the season that remains.

“It’s kind of like spring training,” Cole said. “If you have a bad spring training, you’re like, ‘Well, it doesn’t really matter.’ If you have a good spring training, you’re like, ‘Well, it doesn’t really matter,’ but it feels a whole lot better than getting your ass whacked for three weeks.”

There are two reasons not to get carried away with Cole’s outstanding April. The first is Cole’s appeal to the small sample size — he’s quick to point out he still has 27 more starts to make this season. The second is informed by Cole’s track record in both amateur and pro ball over the past decade. If you looked at Cole as a teenager and looked at him now, the question wouldn’t be “How is he pitching like the best pitcher in baseball?” No, it’d be: “Why the hell did it take him so long?”

Even in the post-Moneyball “not selling jeans” landscape, it’s hard to shake the mental image of what an ace looks like. In reality, aces come in all shapes and sizes, from tiny fast-twitch gymnasts like the young Tim Lincecum to languid left-handers like Randy Johnson. But there’s still an archetype.

An ace has to not only be able to dominate when he takes the mound, he has to be able to take the mound 30-plus times a year for 200-plus innings. That requires not only an explosive athleticism but a physical sturdiness. The ace has to navigate the ineffable pressures of Taking The Ball For The Big Game, which requires not only a swagger but a trustworthiness. It’s preferable, but not necessary, for the ace to be able to intimidate hitters with a stare. He doesn’t need to have a beard, but you’d feel better if he could grow visible stubble between his morning shave and a 7:05 p.m. first pitch. This Hemsworthian physical package is a lot to ask of one guy, so when you find it, it’s pretty exciting.

The ideal form of this archetype was the young Roger Clemens: inexorable, and also indefatigable. Powerful, and also low-key thicc. Capable of burning a hole in your bat with his fastball, or failing that, his eyes.

Sometimes, a young pitcher has to develop that kind of body, or the multipronged arsenal that an ace must command, but Cole was a prodigy, already listed at 6-foot-3, 195 pounds, with good command of an upper-90s fastball and multiple potential plus secondary pitches. The Yankees took him 28th overall out of Orange Lutheran High School (so named for its location in Orange, California, and not because of a belief that one of the 95 Theses was about spray-tanning, to my profound disappointment). Cole might have gone higher if his reported $6 million asking price hadn’t scared off potential suitors earlier in the draft.

Ultimately, the Yankees balked at Cole’s demands as well, and he rebuffed the Bronx Bombers in favor of three years at UCLA. Over those three seasons, Cole led his team to the College World Series final in 2010 and played with six other pitchers who reached the big leagues, most notably Trevor Bauer. By the time Cole was done at UCLA, he’d grown another inch and put on 25 pounds, and his fastball bumped up against 100 miles per hour. Just throwing that hard will get scouts’ attention, particularly when that velocity resulted in success against tough college competition, and Cole was rewarded by becoming one of just 18 players in baseball history to be selected in the first round twice.

The 2011 draft class was the best of the past decade: Dylan Bundy, Anthony Rendon, Archie Bradley, Francisco Lindor, and Javy Báez all came off the board in the top 10, while José Fernández, Sonny Gray, Joe Panik, Jackie Bradley Jr., and Michael Fulmer were all off the board by the end of the first round. Even in the face of that stiff competition, Cole went no. 1 overall to the Pirates, and Bauer went two spots later to Arizona. It was the first time college teammates had gone in the top three of the same draft since 1978, when Arizona State’s Bob Horner and Hubie Brooks went first and third, and it hasn’t happened since.

Cole went no. 1 because he was the prototypical ace, but Bauer was the better college pitcher. In 2011, Cole went 6–8 with a 3.31 ERA and struck out 119 in 114 1/3 innings. Bauer went 13–2 with a 1.25 ERA, threw 10 complete games including three shutouts, and struck out a staggering 203 batters in 136 2/3 innings, en route to the Golden Spikes Award, baseball’s Heisman Trophy. In WHIP, Cole trailed not only Bauer but the Bruins’ no. 3 starter, freshman Adam Plutko, now of the Cleveland Indians. The only statistical category Cole beat Bauer in was BB/9 ratio.

“I’ve always been a pretty good strike-thrower,” Cole said. “If there’s a fault of mine, that’d be it. If I’m going to miss, I want to challenge him — it’s how I was brought up.”

Cole says his insistence on throwing strikes dates back to his youth, but while at UCLA, he spent three years under assistant coach Rick Vanderhook, who might be American baseball’s leading proponent of pounding the zone. When Cole and Bauer went pro, Vanderhook took the head-coaching job at Cal State Fullerton, where his teams now consistently lead the nation in K/BB ratio. One of Vanderhook’s star pupils was Thomas Eshelman, a second-round pick in 2015 who’s now pitching in the Phillies’ minor league system. He walked just three batters in 115 2/3 innings as a freshman and 18 in a 375-inning college career. During his junior year at Fullerton, Eshelman told me a story about how he had a shutout going in the eighth inning of a game against Oregon when he walked a batter on four pitches. Vanderhook came to the mound immediately and told Eshleman that if he walked anyone else, he’d be removed from the game.

As a pro, Cole’s been all too happy to pound the strike zone, and with his stuff, why wouldn’t he? When I suggested to him that it’s easier to challenge hitters when you’re throwing 98, he said, “You can do that when you’re not,” which seems like the kind of thing that’s easy to say when you’ve got a 98 mph fastball.

From the moment he reached the bigs in 2013, Cole immediately became the most celebrated pitcher on the Pirates. In a rotation of veterans enjoying their last days in the sun, Cole was the up-and-coming star, the first of what Pirates fans hoped would be a legion of gigantic young frontline starters. And while 6-foot-5 Jameson Taillon and 6-foot-8 Tyler Glasnow sorted themselves out in the minors, Cole became a mainstay in the big league rotation, bouncing between a floor of reliable competence and a ceiling of a top-five Cy Young finish in 2015. As a rookie in 2013, Cole made two starts in the Pirates’ five-game NLDS loss to St. Louis, then took the ball against Jake Arrieta in the 2015 National League wild-card game. He lost, but this was during that stretch when Arrieta didn’t lose to anyone, so c’est la guerre.

But Cole’s aggregate numbers over five years in Pittsburgh don’t look like they’d belong to a pitcher who could stand up to peak Jake Arrieta. Cole averaged 156 innings on 25 starts per year, with a 112 ERA+ and a K/9 ratio of 8.4. That’s good, for sure, but it doesn’t remind anyone of Roger Clemens.

When Cole is on, hitters see an endless stream of outrageous pitches, from the fastball to a biting slider to a dizzying changeup. They’re tough to hit, and because Cole throws so many strikes, batters can’t just take pitches until they can get something to hit. Where Cole got into trouble, during his occasional struggles in college and the pros, is that everything he threw was hard.

The explicit primary purpose of the changeup is that it looks like a fastball coming out of the pitcher’s hand and breaks like a fastball, but comes in slower than expected, so the batter can’t tee it up. Cole’s problem was that his changeup and slider sit in the high 80s, and if he’s not throwing the absolute bejeezus out of his fastball, the speed differential between the heater and the changeup and slider was only 6 to 8 miles per hour, which wasn’t enough to fool hitters.

Cole’s solution is the knuckle-curve. It’s not particularly common for pitchers to throw both a slider and a curveball, because it’s tough to keep two breaking ball grips and releases straight — in a worst-case scenario, the two pitches blend into one mushy pitch. But Cole’s slider and curveball grips are so different that he doesn’t run into that problem.

“A.J. Burnett introduced me to the curveball my first big league camp, and I always used it as a pitch that was trying to get guys off the fastball — a differential type of pitch, because I can throw it anywhere from 77 to 83 or 84,” Cole said. “So it was always a second complement, and I throw [my two breaking pitches] so differently that they don’t blend.”

The other pitch Cole learned upon reaching the majors was a sinker, a hallmark of Pirates pitching coach Ray Searage, who’s made a career by rescuing pitchers who looked like they had one foot out the door: Francisco Liriano, Edinson Vólquez, and J.A. Happ, just to name three. So Cole started using his sinker about one-sixth of the time and phasing out his changeup for his curveball.

But even as he evolved as a pitcher, Cole invited the same criticisms — the stuff always looked fantastic, but the results, particularly the strikeouts, never lived up to it. Even in 2015, when Cole posted a 149 ERA+ and finished fourth in Cy Young voting, he still came in just under a strikeout per inning. In the past couple of years, Cole got old enough that the Future Ace label wore off, and he settled into being a slightly-better-than-average pitcher with really good stuff.

Cole’s value fell to the point where, despite coming off a 200-inning league-average season, with two years of team control remaining, the Astros were able to get him for just Colin Moran, Jason Martin, Michael Feliz, and Joe Musgrove, four mostly fully developed young players who could end up as two middle-relief arms and a pair of bench bats. That’s a fraction of what the Cubs paid for José Quintana last summer, or what the Yankees paid for Sonny Gray. In terms of impact, the Rangers probably got more for two months of Yu Darvish than the Pirates did for two years of Cole. That speaks volumes about how far his stock had fallen. And if he hadn’t changed upon arriving in Houston, this first month would look like a fluke.

Two weeks ago, The Ringer’s Ben Lindbergh wrote about pitchers who are finding success by living mostly outside the strike zone, including Cole’s Astros teammate Lance McCullers. But Cole is as inveterate a strike-thrower as ever — he ranks fifth among 92 qualified starters in percentage of pitches within the zone.

The big change in Cole’s game has been on his four-seam fastball, which is spinning slightly faster than it did last year, which is interesting but not the point. The point is, at least in the early going, opponents are slugging just .192 on Cole’s fastball, down from .453 last year, and missing it about 50 percent more than they did last year. Bauer, incidentally, is currently beefing with several of Cole’s teammates after he insinuated that the Astros’ staffwide success is the result of doctoring the baseball. Cole’s explanation, unsurprisingly, is more mundane.

“I’m trying to throw the best [fastball] I can,” Cole said. “I’m trying to stay behind it better, stay on top of it, but also just use the four-seamer regularly.”

That last part is the key. Last year, 16.48 percent of the pitches Cole threw were sinkers. This year, that number’s down to 4.16. He’s effectively junked his sinker, and is instead using the four-seamer as his only fastball, while relying a little more on his breaking pitches.

Cole didn’t come out and say this, but it’s possible that he was experiencing the same kind of confusion between his four-seamer and sinker that other pitchers experience between two breaking pitches. What’s more likely is that Cole is finally pitching to the 2018 version of baseball, rather than the 2013 version.

Until recently, hitters were taught to swing down at the ball, taking a direct swing path while simultaneously creating backspin, which would keep the ball in the air longer and allow it to travel farther. Over the past two or three years, a few iconoclastic hitting coaches have begun to teach the opposite, leading to a common swing path that results in a slight uppercut. Rather than attacking the ball from above and hoping to drive it with spin, these hitters attack from below and elevate. This approach doesn’t work for everyone, but you’ll recognize its adherents — Josh Donaldson, Daniel Murphy, José Bautista, Justin Turner — from slugging percentage and home run leaderboards all over the 2010s.

If you throw a sinking fastball into the old orthodox swing plane, hitters would tend to swing over the pitch, driving it harmlessly into the ground. A sinking fastball thrown into the new, upward-arcing swing plane, however, would meet the bat flush and come screaming back at the pitcher like a golf ball off a trampoline. The best way to attack the soft uppercut of the Swing Plane Revolution is by elevating four-seamers. That changes the hitter’s eye level from the low breaking ball, and even if he does make contact, that contact is often a weak pop-up. The sinker isn’t obsolete — Shohei Ohtani throws a slower sinker with more break that he uses to get swings-and-misses, for example — but for Cole the pitch had outlived its usefulness.

So I put it to Cole in so many words — does throwing the sinker invite harder contact against hitters with upward swing planes?

“I think there’s a lot of truth to that statement,” he said.

Even if Cole regresses — and he will, because his strikeout rate would be a record for a qualified starter and his ERA would be the second-lowest of the past 20 years if he kept those numbers up — he’s adapted to the modern game, with spectacular results.

Michael Baumann