WEEI radio here in Boston is reporting that Theo Epstein will leave his position as General Manager of the Boston Red Sox to join the front office of the Chicago Cubs. The Cubs haven’t given Epstein a formal title but he will have considerably more responsibility and higher compensation. The deal is worth more than $15 million over five seasons.

Epstein has been the Red Sox GM since 2003. He was offered the position after Oakland Athletics GM Billy Beane turned it down as documented in Moneyball (both the book and the movie.) The Red Sox hired Epstein at the age of 28 which made him the youngest GM in MLB history. Epstein played a crucial role in hiring Terry Francona to succeed Grady Little as manager and was also instrumental in signing David Ortiz, extricating Kevin Millar from his contract with the Chunichi Dragons and acquiring pitcher Curt Schilling from the Arizona Diamondbacks. In 2004, the Red Sox won their first World Series in 86 years. Another World Series title came three years later. The Red Sox reached the post-season in six of the nine years Epstein was GM.

Although Epstein had his share of influence Red Sox President Larry Lucchino often put the kibosh on his ideas. As a result of this, Epstein would briefly leave the GM job following the 2005 season. Epstein was temporarily succeeded by Jed Hoyer and Ben Cherington. Hoyer would subsequently become the GM of the San Diego Padres while Cherington is widely expected to take over the reins from Epstein.

Notwithstanding the Red Sox collapse last month, Epstein had probably gone as far as he could go at Fenway. It appears that this feeling was probably mutual as evidenced by Red Sox principal owner John Henry’s public statement that Epstein wasn’t going to be the Red Sox GM forever. So Epstein going to Wrigleyville is probably best for all parties concerned.

Of course, the $64.37 question is who will Epstein name to manage the Cubs. It’s doubtful he’ll stick with Mike Quade. Will Terry Francona reunite with Theo in Chicago? Maybe. But there will be pressure brought to bear on Epstein to hire Cubs legend Ryne Sandberg. That won’t be a hard sell. Indeed, Epstein offered Sandberg a chance to manage the Pawtucket Red Sox in 2011 although he would opt to manage the Lehigh Valley Ironpigs in the Phillies organization instead. Interestingly, the Ironpigs beat the PawSox in the International League’s Governor’s Cup semifinals.

Whoever Epstein decides to put in the Cubs dugout, should the Cubs win the World Series in the next five years he will have written his ticket to Cooperstown.