The Boston Red Sox sound convinced that 41-year-old Koji Uehara can pitch, but the question is how they go about keeping the free agent right-handed reliever.

"Koji's done an unbelievable job for this organization," president of baseball operations Dave Dombrowski told a news conference on Tuesday.

Dombrowski said any decision would need to factor in both Uehara's effectiveness while considering the uncertainty that comes with his age.

"But . . . Koji's a hard guy to evaluate, because he's a very abnormal type pitcher," Dombrowski said. "I mean how many guys that are throwing 88 mph (141 kph per hour) and blow the ball by you on a consistent basis? So he's a tough evaluation no matter what."

During the regular season, Uehara struck out 63 batters in 47 innings as the Red Sox's setup man.

When asked about fellow Japanese reliever Junichi Tazawa, Dombrowski stated that the right-hander had gone through an injury and had been unable to hold down his previous job as the eighth-inning setup guy.