Theo Epstein, the former general manager of the Boston Red Sox, is leaving Major League Baseball to become a senior advisor and part owner of Fenway Sports Group, the company announced on Friday. Epstein, who was a driving force behind some of the most recent rule changes in MLB, will continue to hold an informal position on the league’s competition and on-field committees.

The Red Sox, the NHL’s Pittsburgh Penguins, RFK Racing, Boston Common Golf, and Liverpool F.C. are just a few of the professional sports teams and organisations owned by the Fenway Sports Group.

“There is no question that Theo left an indelible mark on our history that represented a transformative era,” Fenway Sports Group owner John Henry said in a statement. “Theo won three World Series titles along the way (2004 and 2007 with the Red Sox and 2016 with the Cubs), exorcising longstanding curses in both Boston and Chicago.

Epstein, 50, came to prominence as a member of the Red Sox front office, serving as general manager from 2003 to 2011.” He left the Red Sox to take over as president of baseball operations for the Chicago Cubs, a position he held until after the 2020 season.

In the same release, Epstein said, “I am thrilled and honoured to return to FSG, to join John, Linda, Tom, Mike, Sam, and the ownership group, and to serve in this new role.” “I have the possibility to work with individuals who are very important to me, push myself in new directions, and use my expertise and viewpoint to support others in reaching their goals and succeeding at the greatest level. This is a genuinely exceptional opportunity for me.