The Cubs will hold a news conference on Tuesday, at which time they will announce the hiring of Epstein. Also Tuesday, the Red Sox are expected to elevate assistant GM Ben Cherington. While Cherington has long worked under Epstein, he actually predates his former boss in the Red Sox organization.
Cherington was hired by the Red Sox in 1999 as a mid-Atlantic area scout and joined the baseball operations department in May of that year. The New Hampshire native was named the club's director of player development in 2002 and served in that role until December 2005, when he became co-GM of the Red Sox, along with Jed Hoyer, when Epstein resigned from the GM post for two months. Cherington worked as vice president of player personnel for three years before being promoted to the role of assistant GM in January 2009.
Multiple reports have Epstein hiring Hoyer, currently the Padres' general manager, to become the Cubs' GM. San Diego will receive a player to be named later as compensation for losing Hoyer, according to a source. Epstein also was expected to add Padres assistant general manager Jason McLeod to the Cubs' staff, according to multiple reports. McLeod was the director of amateur scouting in Boston with Epstein. Among the players he picked in the First-Year Player Draft were Dustin Pedroia, Jacoby Ellsbury, Clay Buchholz, Daniel Bard, and Justin Masterson.
The Red Sox won the World Series twice in Epstein's regime -- the first titles for the baseball-crazed city of Boston since 1918. Now, Epstein will try to help the Cubs end an even more epic drought.
The Cubbies last won the World Series in 1908 and have the longest championship drought in North American professional team sports.
Epstein's departure comes after days of rampant speculation, and two months after reports first surfaced that he might have interest in exploring a new opportunity with the Cubs.
Epstein leaves with one year remaining on his contract with the Red Sox. In a joint statement released on Friday, both clubs "reached agreement regarding a process by which appropriate compensation will be determined for the Red Sox and that issue will be resolved in the near term."
Following a third-place finish in 2010, Epstein made a blockbuster trade with the Padres to acquire All-Star first baseman Adrian Gonzalez and then signed free-agent left fielder Carl Crawford for seven years and $142 million during the offseason, and the Red Sox were touted as championship favorites by several major publications.
It seemed unfathomable back then that Epstein and manager Terry Francona would both be gone shortly after the 2011 season.
But once the Red Sox suffered the worst September collapse in Major League history, blowing a nine-game lead amid a 7-20 month, the shakeup became less surprising.
The Cubs have been looking for a new leader for their front office since Jim Hendry was dismissed as GM on Aug. 19. He took over in July 2002 and put together teams that reached the postseason in 2003, '07 and '08.
Cubs chairman Tom Ricketts had said he wanted to hire someone from a winning organization who would emphasize player development while making winning at the big league level a short-term goal. Given his experience in building Boston's 2004 and 2007 World Series champions, Epstein certainly fits.
"I think one thing you've seen in baseball over the last few years is that turnarounds can happen pretty quickly," Ricketts said on the last day of the regular season in San Diego. "I don't think it's meaningful to describe a year as a rebuilding year or a reloading year or any of that.
"The fact is, [if] you get the right players on the team and they all stay healthy and they play hard, a team can go from 70 wins to 90 wins. It happens pretty frequently. Look at the Diamondbacks, look at the Cubs a few years ago. Things turn around fast, and that's the way we look at things."
The Cubs went 71-91 in 2011 and finished 25 games out of first place, but hope that Epstein helps to spearhead a quick turnaround.
Though Epstein's Boston regime ended without a postseason victory in his final three seasons, the Red Sox having been swept in the 2009 AL Division Series, his tenure was memorable and largely successful. Epstein was hired on Nov. 25, 2002 -- making him at the time the youngest GM in baseball history at 28 years old.
His teams made it to the postseason six times.
In Epstein's first season, the Red Sox advanced to Game 7 of the 2003 American League Championship Series against the Yankees, holding a three-run lead with five outs to go, only to lose in 11 innings.
But all of the pain from that loss went away the following October, when the Red Sox became the first team in history to overcome a 3-0 deficit in a postseason series, defeating the Yankees in a seven-game ALCS and sweeping the Cardinals in the World Series.
Three years later, the Sox again won it all, overcoming a 3-1 deficit to the Indians in the ALCS and this time sweeping the Rockies in the World Series.
In 2008, the Sox were again on the brink of getting to the World Series, only to lose Game 7 of the ALCS to the Rays.
But the momentum changed the past three seasons. The 2009 Sox were swept in the Division Series by the Angels. The past two years, the Sox didn't make the postseason.
Less than 48 hours after the 2011 season ended with a walk-off loss in Baltimore, Francona and the Red Sox had a mutual parting of the ways.
Epstein -- who grew up in Brookline, Mass., about two miles from Fenway Park -- had come under fire the past couple of years for the lack of success of major free-agent signings.
John Lackey, who left the Angels and signed a five-year, $82.5 million contract with the Sox in December 2009, has struggled mightily since his arrival.
Crawford had a near-season-long slump in 2011, hitting .255 with 11 homers, 56 RBIs and a .289 on-base percentage.
When Epstein joined the Red Sox, he proclaimed that the franchise would turn into a scouting and player-development machine.
He backed that up, as Boston produced homegrown stars like Jonathan Papelbon, Pedroia, Ellsbury and Jon Lester.
However, Boston's farm system has experienced a lull at the upper levels the past couple of years, and Epstein used three top prospects to land Gonzalez, a move that has looked good so far. Epstein also traded a developing Masterson on July 31, 2009, to acquire Victor Martinez, who was an impact hitter during his year-and-a-half stay in Boston. Masterson is now a cornerstone in the Indians' rotation.
The last time Epstein left the Red Sox in 2005 -- he escaped Fenway Park on Halloween wearing a gorilla suit -- he returned two months later.
This time, however, there is no turning back, as the separation between Epstein and the Red Sox is very real.