Red Sox manager Alex Cora announced the move in a radio interview. Boston had to clear a rotation spot with the return of Garrett Whitlock, who is scheduled to start.
The 37-year-old Kluber is 2-6 with a 6.26 ERA in his first nine starts for the Red Sox, who signed him to a one-year, $10 million contract in the offseason. Although he was Boston’s opening day starter, Kluber has pitched six full innings just once this season while issuing 18 walks in 41 2/3 innings.
Kluber has been a starter for nearly all of his 13-year major league career. His only relief appearance since 2013 was for Tampa Bay last October, when he gave up a 15th-inning homer to Cleveland rookie Oscar Gonzalez to end the longest scoreless postseason game in major league history as the Guardians eliminated the Rays in the Wild Card Series.
Kluber won his two Cy Young Awards during nine seasons in Cleveland. Boston is his fourth new team in the last four years.
Red Sox move Kluber to bullpen with Whitlock’s return originally appeared on NBCSports.com