Outside of signing Lucas Giolito, the Boston Red Sox didn’t make any notable upgrades to their starting rotation this offseason.

But an unheralded signing this winter could prove to bring added depth to the rotation.

Cooper Criswell, who signed a one-year deal worth a reported $1 million with the Red Sox in December, has only pitched in 12 big-league games in his career with two of those being starts. All 10 of the right-hander’s outings with the Tampa Bay Rays this past season came as a reliever, but the Red Sox want Criswell ready to take on a starting role as he ramps up for a new season.

“They want me to come to spring training prepared to be a starter,” Criswell told reporters at Winter Weekend, per MassLive’s Christopher Smith. “Just because it’s easier if they want to move me into a bulk role out of the bullpen or even a reliever. Obviously it’s easier to transition from a starter to a reliever rather than a reliever to a starter. So I’m going to be geared up, ready for spring training to go as a starter.”

Criswell does have experience as a starter, but it hasn’t come in the majors. The 27-year-old made 17 starts for Triple-A Durham last season, posting a 4-4 record with a 3.93 ERA to go along with 80 strikeouts in 84 2/3 innings. He also registered two saves.

Smith noted that Criswell has one minor league option remaining and could start the season with Triple-A Worcester. That seems likely if the Red Sox use Criswell as a starter rather than a reliver.

It would be tough for Criswell to crack Boston’s starting rotation out of spring training with it once again featuring a logjam of arms with Giolito, Brayan Bello, Tanner Houck, Garrett Whitlock, Kutter Crawford and presumably Nick Pivetta, who found success as a bulk reliever in 2023, competing for spots.

But Criswell is all in on the plan Red Sox chief baseball officer Craig Breslow and new pitching coach Andrew Bailey have for him.

“I loved what they both (Breslow and Bailey) had to say,” Criswell said, per Smith. “I really think they like my arsenal of the movement of the sinker and sweeper. And then focusing in on that cutter. And then the changeup has improved, too, the past two years. So I think just really focusing in on that cutter. Me and (Bailey) have been doing a little throwing program Driveline-wise, trying to gain a little velo here and there. So if I could be able to do that, that would be awesome.”