The Red Sox starting rotation is beginning to come into focus.

Sunday morning Red Sox manager Alex Cora announced that right-hander Josh Winckowski is being moved to the bullpen, leaving four remaining candidates for the last three rotation spots that haven’t been officially locked up.

Brayan Bello and Nick Pivetta are already in and Kutter Crawford is believed to be the favorite for the third spot, leaving Tanner Houck, Garrett Whitlock and Cooper Criswell as the remaining contenders duking it out over the final week of camp.

After originally reaching the majors as a starter in 2022, Winckowski moved to the bullpen last season and enjoyed considerable success. The 25-year-old right-hander appeared in 60 games and posted a 2.88 ERA over 84.1 innings, ranking as one of Boston’s most effective and versatile high-leverage relievers.

Winckowski was given the opportunity to start again this spring, but his performance hasn’t measured up to his competitors. Through four Grapefruit League appearances he trails Houck, Whitlock and Criswell in ERA (4.76), opponent average (.273), walks and hits per innings pitched (1.24) and has fewer than half as many strikeouts (six). He also endured a rocky outing his last time out, allowing six runs (five earned) over 3.2 innings in Thursday’s loss to Philadelphia.

Now he will presumably return to the high-leverage relief role that suited him so well last season.