This weekend in Anaheim, Andrelton Simmons and Didi Gregorius will stand on the same stretch of dirt on the left side of the infield at Angel Stadium, roughly 148 feet from home plate. Simmons, the Los Angeles Angels’ shortstop, will have custody of the dirt during home half-innings, and Gregorius, his New York Yankees counterpart, will have visitation rights during the bottom half of each frame.

That’s where the similarities between the two players start, but the resemblance extends far beyond their positions and the ballpark they’ll share for one weekend series. Both players are 28 and debuted in the majors in 2012; Simmons beat Gregorius to birth by five months and to the big leagues by three. Both were similarly rated as prospects, well below the top tier, and labeled as players whose gloves would get them to the majors but whose bats might never be better than bottom-of-the-lineup material. Both were traded after early offensive struggles seemed to confirm the latter part of that projection, and both have broken out as hitters with their current teams, becoming all-around stars who rank among the game’s most valuable position players since the start of last season. And both began their baseball journeys as teammates on a much bumpier middle infield on the island of Curaçao, where they first played together when Gregorius was 6 and Simmons was 7. They’ve come a long way from Marchena Little League, but they’ve followed nearly parallel paths, leaving a long line of head-shaking hitters—and, lately, roughed-up opposing pitchers—in their mutual wake.

Simmons was born on Curaçao, a small island in the Dutch Caribbean region with a current population of roughly 160,000. Gregorius, whose father and grandfather were high-level players in Curaçao and the Netherlands, was born in the latter and moved to the former when he was 6. He met Simmons almost immediately. “We knew each other, we went to the same school, we played on the same team, [ages] 6 till 16,” Gregorius says. Simmons played soccer, and both played basketball and baseball, with Simmons manning shortstop and Gregorius, his constant double-play partner, playing second.

Gregorius played his way off the island first, signing with the Reds for $50,000 in 2007 and making his pro-ball debut in 2008. Simmons, who didn’t draw the same attention from scouts as a teenager and thought his athletic career was over at age 18, might have fallen out of the player pool had he not been spotted and signed by a baseball coach at Western Oklahoma State. In Division II, Simmons made up for his later start in the States, impressing scouts enough in his sole college season to be drafted by the Braves in the second round in 2010. In addition to playing shortstop, Simmons pitched in relief for Western Oklahoma and touched 98, but he preferred an everyday role to working only off the mound, as Atlanta initially envisioned. “When I was younger and coming up in the minors, I was hoping maybe I could turn into that guy that did a little bit of pitching and hitting,” says Simmons, who’s now teammates with two-way outlier Shohei Ohtani. “But with how much time I have to spend on the offensive side working on it and maintaining my defense, I wouldn’t know where to put the pitching side in.”

“They basically paint you as a one-trick pony. I don’t know if there’s many people that expected me to make adjustments and grow as a hitter.” —Andrelton Simmons

Simmons and Gregorius still practice and train together during their offseasons in Curaçao, which despite its limited population has become a baseball hotbed in the years since trailblazing big leaguer Hensley Meulens broke the seal by making the majors in 1989. Although Andruw Jones remains the island’s most accomplished export, he may one day be eclipsed by someone from the current crop of Curaçaoan players, which includes not only Simmons and Gregorius, but also their former Little League teammate Kenley Jansen, Jurickson Profar, Jonathan Schoop, and Ozzie Albies. “Look how far we all have come,” Gregorius says. Throughout the season, each member of the small but skilled group keeps tabs on the others’ performance. “I know he’s doing good right now,” Simmons says about Gregorius. “I’m happy for him.”

“Doing good” vastly undersells Gregorius’s start to the season. Through Wednesday, Gregorius had been the most valuable player in baseball, amassing 2.2 wins above replacement, according to FanGraphs. Gregorius is mashing to the tune of a .354/.452/.793 slash line, and his nine homers trail only Mike Trout’s 10. On Wednesday, he flashed every skill in his expanding portfolio, homering for the fourth consecutive game and also reaching base via two walks and two singles, one of which was a bunt against the shift. For emphasis and style, he also ended the game on a bang-bang play that wouldn’t have worked without a beautiful barehanded charge.

Simmons is no slouch at the plate either, hitting .318/.396/.471. Through Wednesday, he and Gregorius (who missed almost all of last April after hurting his shoulder in the World Baseball Classic) ranked 15th and 16th, respectively, among all position players in FanGraphs WAR since the beginning of 2017, and third and fourth among shortstops, tenths of a win behind Francisco Lindor and Carlos Correa.

Lindor and Correa were always slated to be superstars: They were first-round picks who perennially ranked among baseball’s top prospects and excelled from their first days in the majors. The extent to which Simmons and Gregorius have blossomed is a much bigger surprise. Each of them appeared on only one Baseball America top-100-prospects list apiece, with Simmons placing 92nd in 2012 and Gregorius ranking 80th in 2013. “A lot of scouts thought Simmons probably should pitch, and I think a lot of people debated whether Didi was ever going to hit,” says Jim Stoeckel, the former Reds scout who signed Gregorius.

Blurbs about the two players in old editions of the Baseball America Prospect Handbook tell the tale. Praise for their defense was universal: The 2011 edition complimented Gregorius on an arm that “allows him to make any throw,” as well as “above-average speed and quick feet,” “good range,” and “excellent body control and fluidity,” culminating in a projection as an above-average major league shortstop. The same book called Simmons “the best defensive player available in the 2010 draft,” salivating over his arm and also citing his “athletic actions, excellent range, soft and quick hands and an incredible feel for the position.” Those reports were dead on: According to ultimate zone rating, Gregorius has been 2.3 runs better than the average MLB shortstop per 150 games played, while the slightly slower Simmons—who’s been by far the most valuable defender at any position since 2012, even though his sprint speed is barely above league average—has a career rate of 17.2 UZR/150, justifying the decades-old decision to station Gregorius at the keystone when the two played side by side. Both were among the 14 shortstops last season with at least one Statcast-tracked throw of 90 mph or more.

Glowing words about the duo’s defense kept coming throughout their minor league careers, but expectations for their offense were much more muted. The 2010 BA book described Gregorius as a “solid bunter” who had “very little power.” The next year added the epithet “relatively helpless against lefties,” while 2012 chipped in “rarely walks” and upgraded his power to “well below-average.” Gregorius’s last Handbook appearance, in the 2013 edition, which arrived after he’d made his major league debut (and featured the more highly regarded Profar on the cover), contributed “too aggressive” and “needs to use the whole field more.” That section summed up, “Scouts are divided on Gregorius’ bat,” which was probably better than they had been before. Even Stoeckel recalls a conversation in which he asked, “Didi, I know you want to play shortstop, but if the bat doesn’t work out would you want to go to the mound?”

The early verdict on Simmons was along the same lines. “The question mark is Simmons’ bat,” said the 2011 Handbook, which warned that “his swing is long and he’ll have to work on his approach to succeed against more advanced pitching.” In 2012, BA noted that Simmons “doesn’t walk much” and “won’t have more than gap power.” The reports sprinkled in some positives, noting both players’ bat control and ability to make contact, but their minor league numbers never stood out. Consequently, neither player ever ranked higher than fourth among his own organization’s prospects. The statheads weren’t wowed, either: Baseball Prospectus 2013’s Gregorius comment concluded, “Think Alfredo Griffin,” thereby comping him to a player with a career 65 wRC+.

The slights from the naysayers have stuck with both players. “I don’t think there were many people that expected me to produce much offensively,” Simmons says, adding, “They basically paint you as a one-trick pony. I don’t know if there’s many people that expected me to make adjustments and grow as a hitter.” Gregorius also remembers hearing the frequent refrain that his bat might not develop. “Everybody said that,” he says, repeating, “Everybody said that.” To be fair, he allows, he didn’t expect himself to hit for as much power as he has since last season.

Simmons held his own at the plate in his partial first season in Atlanta, and in 2013, he and Gregorius posted identical 91 wRC+ marks, above the 86 average for all shortstops that year. After that, though, their bats tanked. Both posted sub-.300 on-base percentages in 2014, and the extra-base ability that Simmons had displayed as a sophomore—which he attributes to pitchers throwing him hittable pitches out of lack of respect for his power—evaporated. “It’s hard to reconcile how someone so smooth and skillful in the field can look so unbalanced and lost at the dish,” Baseball Prospectus 2015 said about Simmons. The book’s blurb on Gregorius was no better: “Unless or until he can be within shouting distance of ‘tolerable’ on offense, he should be a backup.”

The Yankees disagreed. In December 2014, they acquired Gregorius in the three-team trade that sent Shane Greene to Detroit and Robbie Ray to the Diamondbacks, installing the soon-to-be-25-year-old as the replacement for the just-retired Derek Jeter. When the successor to one of the best-hitting shortstops of all time started at Jeter’s position on April 6, 2015—Gregorius’s first Opening Day start—he carried a career .243/.313/.366 slash line, which he’d compiled in good hitter’s parks in a weaker division and league.

Yankees assistant GM Michael Fishman, who oversees the team’s analytics department, explains that the front office viewed Gregorius as a bounceback candidate, citing his history of making contact in the minors and his hard-luck low BABIP in the majors in 2014. “Obviously, nobody was projecting a … performance like this year,” Fishman says. “But we had a lot of people who thought there was upside. Multiple different scouts projected him as an above-average player. And based on the data, he was someone the quantitative analysis department was pushing for as well.” The trade doesn’t deserve to be mentioned alongside the theft of Babe Ruth from the Red Sox, as one overexuberant writer suggested on Wednesday, but it’s worked out phenomenally for New York. Gregorius, who’s making $8.25 million this season, is under team control through 2019.

Simmons, who’s making $11 million this year, is scheduled for free agency after 2020, although he has a total of $28 million coming to him over the next two years thanks to the long-term extension he signed with the Braves in February 2014. Like Gregorius, Simmons was sent out of town on the heels of a disappointing offensive season—in his case, his second in a row. Of the 22 shortstops with at least 900 plate appearances from 2014-15, only two hit worse than Simmons.

On the other side of the swap was Angels GM Billy Eppler, who was still an assistant GM with the Yankees when they added Gregorius, and pulled the trigger on the trade for Simmons a little more than a month after his hiring in Anaheim. Because Simmons’s glove was so good, he had value even when he wasn’t hitting, which forced Eppler to include Angels top prospect Sean Newcomb in the deal. But Eppler believed that there was more life in Simmons’s bat. “Based on his age and a couple underlying process-based characteristics, we felt there was a reasonable chance for him to improve in the batter’s box,” Eppler says.

“Guys that are committed to continued learning and continued growing evolve, and I think we see this throughout sports, throughout business, throughout life.” —Angels GM Billy Eppler

The two shortstops have more than rewarded Eppler’s and Fishman’s faith. Each one has raised his wRC+ by at least nine points in three consecutive seasons, and given their great starts this season, they’d both have to hit at pre-2017 levels over the rest of 2018 to fall short of a fourth nine-point improvement. Only five previous players in MLB’s modern era—Enos Slaughter, Eddie Yost, Mickey Mantle, Craig Biggio, and Magglio Ordóñez—have pulled off that feat in consecutive seasons of at least 250 plate appearances. More than half of those players are in the Hall of Fame.

Because Simmons and Gregorius have ascended almost in unison, their career stats are somewhat alike; Baseball-Reference lists Simmons as the eighth-most-similar batter to Gregorius on a cumulative level. Neither player acknowledges making a mechanical change that would be obvious to the naked eye—a revamped stance, say, or an overhauled swing—but both have made major adjustments to their approaches at the plate.

Although Gregorius, who hits lefty and is listed as the bigger of the two by an inch and five pounds, has shown much more power this year, Simmons actually hits the ball harder on average. Gregorius just tends to hit it higher, ranking among the league leaders in average vertical launch angle. “He just needed to become a man physically,” Stoeckel says. “I think that’s what’s happened to him. His body has really developed over the last few years.” Gregorius echoes the explanation that his body has changed more than his mechanics. “Even when I was with the Diamondbacks and the Reds I always used to hit fly balls,” Gregorius says. “But now I’m older, I’m stronger, and now they go out.”

While it’s true that Gregorius has never been a ground ball hitter, he has more than doubled his average launch angle since 2015. And as it happens, “since 2015” has been the perfect period to do that, because that’s also the time during which changes in the baseball’s behavior have caused balls in the air to fly farther. Those changes have disproportionately benefited hitters like Gregorius, whose once-warning-track power is now sufficient to send balls into the stands. Last September, FanGraphs writer and xStats proprietor Andrew Perpetua calculated that Gregorius was the home run hitter who’d benefited the most from the ball flying farther in 2017, estimating that more than half of his homers last season would not have gone out if not for that boost from the ball.

Yet Gregorius can’t be a product of the juiced ball alone: This year, with the leaguewide home run rate down and the ball not carrying quite as well, Gregorius is slugging better than ever. That apparent paradox also has an answer: Some of his strides have stemmed from his home park’s configuration.

It’s an understatement to say that Gregorius’s power is to the pull side, as this spray chart of all of his home runs attests.

Particularly since the start of 2017, Gregorius has sent air balls soaring toward the part of the park where those circles are clustered. As the chart below shows, Gregorius has significantly increased the percentage of his balls in the air that are pulled, while also significantly decreasing the percentage of his pulled balls that are hit on the ground.

Whether consciously or unconsciously, Gregorius has targeted Yankee Stadium’s short right-field porch ever more precisely. That progression has paid dividends: Since the start of his Yankees career, Gregorius has generated a .649 weighted on-base average on pulled fly balls (and 25 homers) on the road, and an .816 wOBA (and 38 homers) at Yankee Stadium, in roughly the same number of plate appearances. Gregorius has been in the right place at the right time, but he’s also adapted to take advantage of those circumstances.

Both shortstops have also made one more major change: They’ve stopped swinging at so many balls. Simmons and Gregorius always put the bat on the ball, but that ability to make contact could also be a curse: When they swung at pitches outside of the strike zone, they connected more often than the typical player, which led to a lot of weak contact and easy outs. This year, they’ve dramatically reduced their chase rates: Only two qualified hitters have chased less often than Simmons, and even the more aggressive Gregorius has held his chase rate below the league average. Among the 121 qualified hitters this season who also made at least 450 plate appearances last year, Gregorius and Simmons rank first and fourth, respectively, in year-to-year chase-rate reduction. The two shortstops who were once downgraded as prospects because they didn’t take pitches have walked far more than they’ve whiffed this season, ranking third and fifth in the majors, respectively, in walk-to-strikeout ratio.

Gregorius says the Yankees’ hitting coaches have hammered home a more selective philosophy. “Since pitchers were not trying to throw me a lot of strikes because I would swing every time, they told me try to be more in the zone,” Gregorius says, adding, “I’ve just been learning to be more patient.” Simmons tells a similar story, although his plate epiphany first struck in 2016. That season, he’d hit .204/.231/.263 (32 wRC+) through June 22. At about that time, Eppler texted Simmons some stats that Simmons says reminded him “how good I am when … I’m actually swinging at pitches I’m good at hitting.” The information, Simmons says, “just made me think a little bit, maybe I’m being too aggressive.” He took the input to heart and worked with the team’s coaches to put a more selective approach into practice. Over the rest of the season, he swung at more hittable pitches and was rewarded with a .315/.363/.412 slash line (115 wRC+).

In subsequent seasons, Simmons has further refined that discipline and built on his success. “I still think I’m aggressive, but I feel like I’m more aggressive in the zone,” he says. In the past, “it could be a fastball, off-speed, didn’t matter. If it was close to the zone, I was swinging.” Now, he adds, “I’m not going to give away an at-bat by chasing pitches as often as I used to. … It makes a big difference.” Occasionally, he gets burned by a borderline pitch, but he’s learned to take the long view. “They call [a strike] every once in a while, and you’re like, ‘Damn, maybe I should have swung,’” Simmons says. “But down the road you’re going to be better off not swinging at [balls], and hoping the umpires make a good call.”

Last Thursday, Simmons performed the type of physics-defying feat that’s always defined his defense, starting an improbable double play with a dive and a flip from his glove.

The perfect feed earned a lot of attention. On the same day, though, Simmons did something less visible that may have been even more valuable: He reached base four times, three times via walks. The game was a testament to the new Simmons, who still makes highlight-reel grabs but now contributes, as Eppler says, “on both sides of the inning.”

“I always used to hit fly balls. But now I’m older, I’m stronger, and now they go out.” —Didi Gregorius

Although it requires considerable talent to morph mid-career after already reaching the highest tier of competition, the way that the two childhood friends have flourished is also a vivid demonstration of the power of players who are willing to learn, especially in an era when actionable information is one text from the front office away. “They’re very bright guys,” Stoeckel says. Simmons could have bridled at the helpful hints from his boss, but by embracing them instead, he unlocked his latent talent. “We all tend to think we’re experts, and we try to forecast and try to look at certain things,” Stoeckel says. But, he adds, “people underplay aptitude.” More and more, teams are trying not to. “In players that we acquire, sign, trade for, whatever, we try to identify their level of open-mindedness,” Eppler says. “Guys that are committed to continued learning and continued growing evolve, and I think we see this throughout sports, throughout business, throughout life.”

In a weekend series that also features Mike Trout, Aaron Judge, and Giancarlo Stanton, Simmons and Gregorius won’t be the most imposing or high-profile players on the field. But they’re as far from being easy outs as they are from the field where they first competed together. “It’s fun to see for both those guys, and for baseball in Curaçao,” Stoeckel says. It’s fun for us, too.

Thanks to Jessie Barbour and Mike Petriello of MLBAM for research assistance.