With the scene of the World Series shifting back to Boston for Game 6, we're here to answer this pressing question: Just who is that guy wearing the big yellow headphones behind home plate at Fenway Park? He has become such a front-row fixture at Red Sox games in the past decade that there is even a Facebook page dedicated to him under the account of Yellow Headphones Guy at Fenway Park.

The short answer is Jeremy Kapstein.

The longer and more complex answer is that he has been one of the most influential people in baseball in the past 40 years, first as a pioneering agent and then as a team executive.

The Red Sox list him in the team directory as their Senior Advisor For Baseball Projects. What does that mean?

"He's part of our intelligentsia apparatus," Red Sox President/CEO Larry Lucchino told the Boston Globe in 2003.

Kapstein, who went to Harvard and Boston College Law School, began his baseball career as an agent in the first years of MLB free agency in the 1970s. Then known as Jerry Kapstein, he represented stars including Rollie Fingers, Fred Lynn, Goose Gossage, Joe Rudi, Don Gullett, Don Baylor and Carlton Fisk.

In 1976, Sports Illustrated wrote a profile on him titled He's Baseball's Not-so-secret Agent:

Armed with individual statistics, comparative salaries and court decisions outlawing the reserve clause, Kapstein is a major influence on the economic structure of the game. "My demands reflect the changing times, but are hardly excessive," Kapstein insists.

In the late '80s, Kapstein shifted to team management, serving as president and later as CEO of the San Diego Padres, while also choosing to go by Jeremy, rather than Jerry.

Although Kapstein left the Padres after a change of ownership, he returned to the team and became an advisor to Lucchino, who came on board a team executive in 1995. When Lucchino moved to the Red Sox in 2002, Kapstein went with him. His seat and his headphones helped him gain a cult following.

Despite his prominent visibility during home games, Kapstein has operated mostly behind the scenes for the Red Sox. The exception was his stint as interim GM during Theo Epstein's short-lived resignation after the 2005 season. Kapstein and Bill Lajoie pulled off a multi-player deal that centered around sending Hanley Ramirez to the Marlins for Josh Beckett and Mike Lowell.

In 2010, he raised his public profile through politics. Kapstein, a Democrat, made a run to be lieutenant governor of Rhode Island. Although he was unsuccessful in trying to land that political seat, don't even think about trying to take his special spot at Fenway: