Free agent reliever Koji Uehara's agent said Tuesday the 41-year-old pitcher can expect a strong market for his services after the Boston Red Sox handed his job to someone else.

His agent, Mark Pieper, said he was having "serious discussions" with at least six big league clubs about Uehara.

On the same day the Red Sox traded for right-hander Tyler Thornburg to pitch in the eighth-inning spot Uehara held down in 2016, Boston's president of baseball operations Dave Dombrowski said the team would not offer the Japanese veteran a contract for next year.

Uehara spent the last four seasons with Boston, where he first signed as a free agent in 2013. Uehara took over the closer's role midway through his first season and contributed to the club's World Series championship.

"Koji will have a market," Pieper told Japanese media at baseball's annual winter meetings outside of Washington. "He was great there, he got a (championship) ring from there and he has nothing but good experiences from there."

This offseason has been a good market for relievers, with Pieper having already negotiated a four-year deal for closer Mark Melancon worth an unprecedented $62 million.

"I think the market will be really good," Pieper said. "Whether Koji will be able to ride that wave along with some of the other pitchers who are older, it's hard to say. Koji will have plenty of opportunities here (in the States)."

Pieper also represents utility infielder Munenori Kawasaki and expressed disappointment that the fan favorite will be unable to secure a major league contract.

"Somebody needs to step up and give him a major league deal," Pieper said. "He could play in the big leagues all year. There's no reason for him to go up and down" between the minors and majors.