Age of the pitcher? Epstein went all out for Jon Lester, but he's building the Cubs off the bats of young hitters. Patrick Gorski/IconSportswire/AP Images

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BILLY BEANE HAD championship aspirations and two pitcher-sized holes to fill. So last April, when Oakland's GM chatted up Cubs president Theo Epstein about right-handed starters Jeff Samardzija and Jason Hammel, he casually mentioned that he'd be willing to discuss star shortstop prospect Addison Russell in trade conversation. Epstein already had an All-Star shortstop in Starlin Castro and a top prospect at the position in Javier Baez. But that didn't matter. As soon as Epstein heard the name Russell, he began stalking the deal relentlessly. Two months later, the trade was complete, and one month ago, Russell, at 21, became the youngest player in the National League.

Later in 2014, Red Sox general manager Ben Cherington, who worked for Epstein in Boston and replaced him when he left for Chicago, began to follow the same approach. He acquired, over three months, third baseman Pablo Sandoval and outfielders Rusney Castillo and Hanley Ramirez, just a few of the many collectibles in his own position-player hoarding.

For the past two decades, with MLB under an offensive explosion, the formula for winning baseball has been clear: Get arms. From the '01 Diamondbacks and '03 Marlins to the '05 White Sox, '08 Phillies and '12 Giants, teams with a few top aces -- often veteran ones -- could trump a full house of sluggers. Pitching was the prized art form, GMs the collectors. Yet here were the Cubs and Red Sox, buying bats in bulk. What were they doing?

WHENEVER HE FINDS himself stumbling upon highlights of Boston's 2004 World Series title, Epstein will cease channel-flipping and settle in to watch. The former Red Sox GM doesn't do this because he's sentimental or he needs to relive the joy but because he doesn't remember them. He literally wonders what comes next.

He does remember edging down to the runway leading to the Sox's dugout in Game 4 because he wanted to know what a Boston championship looked like. He couldn't see home plate, but he heard the ball hit the bat and saw pitcher Keith Foulke bounce off the mound in pursuit of that final out. Epstein knows he hugged somebody. He isn't sure who. And he can recall seeing longtime Boston player, coach and manager Johnny Pesky -- born in the months after the previous Red Sox title in 1918 -- weeping openly, as Epstein did. "A lot of the rest of it," Epstein says, "is very blurry."

Epstein is building the Cubs based on the same principles of the 2004 World Series-winning Red Sox. Raymond Boyd/Getty Images

But what Epstein, Cherington and the rest of his front office did manage to retain was a formula -- the brawny formula upon which they'd built the Sox -- the idea that a team's margin for error could be solved by an overwhelming lineup. They had identified hitters and stacked them throughout, from Twins castoff David Ortiz to former replacement player Kevin Millar to Bill Mueller, who won a batting title in 2003 at the bottom of the Boston order. "When you have a feared offense, one through nine in the American League or one through eight in the National League, it shows up every day," Epstein says.

And it compensates for weaknesses. A starter might have a rough game, or a fielder might make an error, but eventually Johnny Damon, Ortiz and Manny Ramirez would swing their team into the game. "An epic offense," Cherington recalls.

"For whoever was pitching, we wanted 27 outs to be as excruciating as they could possibly be," says Josh Byrnes, who worked for the Red Sox at the time before serving as a general manager for the Diamondbacks and Padres, and, most recently, as a senior vice president for the Dodgers.

The only problem: sustaining it. By 2005, as the implementation of tougher testing for PEDs loomed, execs predicted that offensive production would decline. But they could not have anticipated by how much. In 2000, 47 hitters had 30 or more homers; in 2014, 11 hitters reached that mark. In 2001, two pitchers had ERAs below 3.00; by the end of 2014, 22 pitchers did.

In 2000, 28 teams posted on-base percentages of .329 or higher. By the end of this April, just seven teams were at or above that mark. That those teams included Cherington's Red Sox and Epstein's Cubs was not at all an accident.

IN MAJOR LEAGUE baseball, ideologies are viral; they travel on the backs of host executives. And in 2011, when Epstein left the Sox, he carried with him his unique strain of thought.

Jed Hoyer was part of the Epstein rat pack in the 2004 championship and had been hired by the Padres as general manager in 2009. Two years later, when Epstein vaulted to the Cubs, Hoyer left San Diego -- where his standing was tenuous -- to become Chicago's general manager. And now, as those two men and the rest of the Cubs' new staff began meeting in Epstein's office at Wrigley Field, they studied the theoretical free agent classes of pitchers and position players for the years ahead. That forecast for hitters, they thought, was ugly. Teams were increasingly signing their best young players early in their careers, from Evan Longoria to Troy Tulowitzki, Ryan Braun and Joey Votto. And the free agents who did reach the open market tended to be far out of the Cubs' price range. Albert Pujols signed that winter for $240 million. The next year, Prince Fielder would pocket $214 million. Despite speculation that the Cubs would be heavy bidders on both, they effectively passed.

Although the Cubs believed they could find pitching in the free agent market, they saw investing in position players as the safer play -- like picking U.S. bonds over startup stocks. Still, Epstein and Hoyer determined that they couldn't rely on the market for position players; they would have to find their own, at a time when MLB started building restrictions on how much teams could spend on international players. "It's hard to find bats, but it's even harder to find them in free agency," Hoyer says. "Our thought was, let's be aggressive and build our offense and build our lineup for a long time."

They started by trading pitcher Andrew Cashner to San Diego for the then-unproven 22-year-old first baseman Anthony Rizzo, whom Epstein and Hoyer both knew from previous deals. Two days before the new rules went into effect, the Cubs signed Jorge Soler, a defector from Cuba, for $30 million over a nine-year deal. In the 2012 draft, the Cubs had the sixth pick and selected a prep outfielder, Albert Almora, who three years later has reached Double-A.

The Cubs had the second overall pick in 2013, which meant they were at the mercy of the Astros, who picked first. There was, at the time, a fairly overwhelming consensus about who the best available player was: Kris Bryant, a third baseman from the University of San Diego. Says a rival executive whose team didn't have a top-10 pick: "When we started ranking our board, it was like, 'Kris Bryant's No. 1, right? OK, move on to the next guy.'"

Assuming that the Astros would pick Bryant, the Cubs were prepared to take a starter in Jonathan Gray or Mark Appel. Then the Cubs got lucky: The Astros tapped Appel -- a pick that now appears destined to be as second-guessed as the Trail Blazers' selection of Sam Bowie over a guard named Michael Jordan.

Following in Epstein's footsteps, Cherington's nabbing of sluggers is well-documented, but his approach to pitching has differed. Jim Davis/The Boston Globe/Getty

Meanwhile, back in Boston, Cherington was forging his own path after a tumultuous first season as GM (aka the year of Bobby Valentine). In 2013, drawing on the experiences of 2004, he began to remake the team, filling the lineup with veteran hitters who would compete throughout at-bats -- Mike Napoli, Shane Victorino, Jonny Gomes. It worked well. Famously well. The Sox won the Series on the strength of their bats -- and a postseason pitching run by Jon Lester (4-1, 1.56 ERA).

Their strategy was working, but with Lester barreling toward free agency, Cherington and his staff faced a test of their resolve. While studying pitcher metrics for market inefficiencies, they noted that the age at which pitchers tend to peak was in retreat. Cherington won't reveal the metrics favored by the Red Sox, but the numbers mined by ESPN Stats & Information are striking. In the seasons from 1998 to 2003, an average of 49 pitchers in their 20s posted a WAR of at least 2.0, and 38 pitchers in their 30s did so. Compare that to 2010 to '14, when an average of 61 pitchers in their 20s posted a WAR of 2.0 or higher, but just 24 pitchers in their 30s did the same. The trend was notable and suggested that PEDs had been extending the careers of pitchers every bit as much as hitters. The takeaway for the Sox front office? High-end position players were a better, safer investment, particularly at a time of dwindling run production. So Cherington, like Epstein, began serially dipping into the market's selection of available hitters.

So it was that in the summer of 2014, Boston traded Lester to Oakland for slugger Yoenis Cespedes. Then, the Red Sox signed two Cuban defectors, center fielder Castillo and infielder Yoan Moncada, for about $135 million combined. During the winter, they bid heavily on two experienced hitters known for doing damage against good pitching -- Sandoval ($95 million) and Ramirez ($88 million). And they refused to consider trading catcher Blake Swihart or outfielder Mookie Betts for 31-year-old Cole Hamels, despite the clamoring from Red Sox fans. "You need both pitching and hitting, but maybe there's more you can do to help pitching than hitting," says a GM who's watched the Red Sox work. "It's easier to get pitching."

To build his rotation, Cherington targeted younger, less expensive pitchers. The 35-year-old John Lackey was traded for 26-year-old Joe Kelly. The Sox secured 26-year-old Rick Porcello with a four-year deal for $82.5 million, then traded for 28-year-old lefty Wade Miley and abstained from bidding on 30-year-old Max Scherzer and 33-year-old James Shields.

The upshot is that the Red Sox, like the Cubs, are now sitting on a surplus of bats, with the infield and outfield seemingly two- and three-deep at every spot. (Says one NL executive, "What the Red Sox have done is like a big-market version of the Cubs.") Cherington's peers assume that at some point this season the GM will use his stockpile to swap for precisely the kind of pitchers Boston now covets -- younger, closer to those peak years. "They have the resources to get anybody they want," says one AL executive. "They could probably outbid anybody if they wanted to."

Ironically enough, what Cherington wanted, early this winter, was to get Lester back. Even more ironically, Epstein wanted him too.

WHEN EPSTEIN SET his sights on Lester this offseason, he eschewed the hokey college recruiting stuff and showed Lester and his wife, Farrah, a video, a 15-minute promo with Ryan Dempster and Kerry Wood talking about playing in Chicago. Epstein wanted the whole thing to feel like a family reunion, an appeal from an old friend. But he was also prepared to do whatever was necessary. Knowing Lester's affinity for hunting, he sent him camouflage gear dotted with Cubs logos. "I was ready to soak myself in deer urine if necessary," Epstein later joked with reporters.

For the Cubs, the fight over Lester was an organizational statement, the first real superstar free agent target in Epstein's tenure. Epstein and Hoyer knew the pitcher well from their days together in Boston and knew they'd be landing a rotation anchor. And it was possible, in part, because of how Epstein and Hoyer had collected cheap, young position players, freeing up money.

Of course, the Sox had deep pockets too. The question was whether they'd spend. The previous winter, Boston had offered Lester $70 million over four years, reflecting its reluctance to invest in older pitchers. It wasn't close to where Lester perceived his market value, and some of Lester's teammates were angered by what they thought was a lowball offer. Lester's side ended the negotiations, and for weeks the Sox tried to persuade him to re-engage. On June 29, 2014, manager John Farrell met with Lester, trying to coax him to the table. But after Boston signaled that it would push its offer just a little beyond $100 million, in the range of Homer Bailey's $105 million deal with the Reds, the in-season talks ended. Lester was traded.

Once Lester reached free agency, his market price shot upward; the Cubs pushed, recruiting Lester's personal catcher, David Ross, and their offer to Lester reached $155 million. If Boston was going to land Lester, it needed to go all-in. But for a pitcher beyond his 30th birthday -- even someone they knew as well as they know Lester, his arm and mind -- Red Sox owner John Henry wasn't prepared to do that. Boston offered $135 million, but in the last 48 hours, there were those in the organization who knew it wouldn't be enough. Epstein got Lester, and Cherington went in a different direction -- and it appears he will have to keep doing so.

As Cherington leaned against the Fenway Park batting cage on May 3 and watched Ortiz lash line drives toward the Green Monster, he was aware the Red Sox had the worst rotation ERA in baseball. Just four days later, Boston would fire its pitching coach, Juan Nieves. Help will most surely be needed. A time zone away, Epstein has his own challenges, some inherent to a team relying on all those young players. It may be that the collective potential of Rizzo, Soler, Bryant and Russell -- or Swihart, Castillo, Moncada and Betts, for that matter -- won't fully manifest this summer. But Epstein and Cherington are steps ahead, already in a place other teams are now trying to get to, on the leading edge of baseball's never-ending quest for the undervalued asset.

"Boston's lineup is a joke," a rival general manager told me, meaning that as a compliment, "and if you were picking a team to win multiple World Series in the immediate future, you'd pick the Cubs. They can be that good."

Let the leaguewide hoarding begin.