After a lackluster return to the Boston Red Sox’s rotation, Clay Buchholz once again is bound for the bullpen.

The Red Sox will use Buchholz in a relief role for Boston’s final five games before the Major League Baseball All-Star break, manager John Farrell told reporters after Monday’s 12-5 win over the Texas Rangers at Fenway Park.

Farrell also announced right-hander Sean O’Sullivan, who pitched five innings and earned the win Sunday in his fourth major league start, would get the ball again Friday against the Tampa Bay Rays.

Buchholz’s demotion came two days after he allowed six runs (three earned) in just 4 1/3 innings of work in Saturday’s disastrous 21-2 loss to the Los Angeles Angels. In three starts following his return to the rotation last month, the right-hander has surrendered a total of 14 runs on 18 hits in 14 1/3 innings. He also gave up five home runs over those three games, and the Red Sox lost all three.

Buchholz’s stint as a reliever earlier this season — the first of his career — largely was a successful one. He labored through one forgettable outing in Baltimore (three hits, four runs, four walks in 3 1/3 innings) but did not allow a run in any of his other four relief appearances.

The Red Sox host the Rangers again Tuesday night.

Thumbnail photo via Kim Klement/USA TODAY Sports Images