Theo Epstein’s departure from the Boston Red Sox to the Chicago Cubs caps an unceremonious end to a successful tenure in Beantown.

As of Thursday night, nothing had been made official about a reported five-year/$20 million agreement between Epstein and the Cubs, but sources close to the situation believe a marriage will be consummated soon and that Epstein’s top assistant, Ben Cherington, will replace him as the next general manager of the Red Sox.

When he was hired by the Red Sox in 2002, Epstein inherited a team that fell one game short of the World Series after Aaron Boone’s home run propelled the Yankees to a decisive Game 7 ALCS victory in 2003. Following this defeat, Epstein appeared to have the Midas touch, as his hire of Terry Francona, trade of shortstop Nomar Garciaparra and offseason acquisitions of Curt Schilling and Josh Beckett proved to be instrumental to the team’s championship runs in 2004 and 2007.

The dominance of the Red Sox during this four-year span (2004-08) transformed the perception of an organization once mired in mediocrity to a model franchise on the precipes of success that mirrored the Yankees of the late ’90s.

But 2009 marked the beginning of a steady decline from greatness for Epstein and the Red Sox. During that year, the team parted ways with disgruntled Manny Ramirez and was eliminated by the Los Angeles Angels in the ALDS. In December 2009, Epstein signed former Angels’ hurler John Lackey to a five-year/$82.5 million contract in hopes of bolstering the team’s rotation. But in two seasons with the Sox, Lackey has posted a 26-23 record and an ERA over 5.00.

In 2010, the Red Sox failed to qualify for the postseason because of season-ending injuries to All-Stars like Dustin Pedroia, Kevin Youkilis and Jason Varitek. In the winter of that year, Epstein targeted the cream of the crop in terms of player personnel when he acquired All-Star first baseman Adrian Gonzalez from the San Diego Padres and signed Carl Crawford to a seven-year/$140 million contract — the most expensive for an outfielder and the second highest in the team’s history. While Gonzalez produced in his first season with the team, Crawford posted a measly .255 batting average with 11 home runs and 56 RBI.

With the acquisition of Crawford, Gonzalez and talented pitchers like Bobby Jenks (Chicago White Sox), Dan Wheeler (Tampa Bay Rays) and Alfredo Aceves (New York Yankees), baseball fans and prognosticators were convinced that Epstein had assembled a “dream team” that was destined to make its return to the Fall Classic in 2011.

But the postseason failures of the Yankees team with its $200 million payroll should have taught us that the most talented team isn’t always the “best team,” or a “team” in the truest sense. Boston’s September swoon proved that the 2011 Red Sox were not a “team,” but a collection of All-Stars plagued by an unmerited sense of entitlement.

While the ineptitude of the Red Sox on the field and the alleged disconnect between players and management behind the scenes has tarnished his legacy to a degree, Epstein is still responsible for ending the 86-year curse of the Bambino in 2004 and developing homegrown stars like Pedroia, Jacoby Ellsbury and Jon Lester, who will be fixtures with the team for years to come.

As he moves on to the Cubs, Epstein will be faced with the similar challenge to transform a losing culture and replenish a farm system that is bereft of young talent. Time will tell whether he will break the 102-year curse of the Billy Goat. Unlike the 2002 Red Sox, who won 93 games, the Cubs have lost 90 games in each of the last two seasons and are saddled with the expensive contracts of Alfonso Soriano (eight years/$136 million) and Carlos Zambrano (five years/$91.5 million). But if he delivers a championship, Epstein will not only earn himself a statue in Chicago, but he will also cement his place in Cooperstown.