Red Sox sign closer Koji Uehara for 2 years

The Boston Red Sox have signed Koji Uehara for two more years, committing $18 million to the reliever who closed out the 2013 World Series but struggled along with the team this season.

One year to the day after Uehara struck out Matt Carpenter to seal Boston's third title in 10 years, the team gave him a deal that will pay him $9 million in each of the next two years, when he will be 40 and 41 years old. General manager Ben Cherington said he thought Uehara had less wear and tear on his arm than other pitchers his age.

''You're really looking at a guy who has been one of the elite relievers in baseball,'' Cherington said in a conference call with reporters on Thursday night. ''We feel really good about the ninth inning when he's pitching out there with a lead. It was a priority for us to retain him.''

Uehara joined the Red Sox in 2013 and inherited the closer's role midway through the season, helping to stabilize the bullpen that was a key contributor to the title. He finished the regular season with a 1.09 ERA and 21 saves in 24 chances and then recorded seven saves and a 0.66 ERA in the postseason, when he was named the MVP of the AL Championship Series.

Uehara converted his first 15 save opportunities this season to run his streak to 31 in a row - the second-longest in franchise history - and made the All-Star team for the first time. In a span of 21 innings from May 3 to June 16, he did not allow a run.

But after making the All-Star game for the first time, Uehara stumbled in mid-August and allowed 10 runs in his next six outings while blowing three straight save opportunities. He finished the season with three scoreless outings and a 6-5 record with 26 saves and a 2.52 ERA.

''We felt really comfortable with where he was and where he will be going,'' Cherington said. ''We were able to look at the whole body of work. He's been an elite performer for two full seasons.''

Before coming to Boston, Uehara spend 10 seasons with Yomiuri of Japan's Central League, leading the Giants to two Japan Series championships. He also pitched for Japan in two Olympics and led the country to the gold medal at the inaugural World Baseball Classic in 2006.

In six major-league seasons with the Orioles, Rangers and Red Sox, he has a 15-15 record with 61 saves and a 2.44 ERA. With 46 walks and 412 strikeouts in 351 1-3 innings, he has the best career strikeout-to-walk ratio and of any pitcher in baseball history with at least 100 innings.

Also Thursday, the Red Sox said that outfielder Rusney Castillo will be held out for the remainder of the Arizona Fall League schedule after straining the muscle between his thumb and fingers.

''It's an injury that will respond well to rest,'' Cherington said. ''It's not a concern moving forward, but we do want to let it calm down.''

On the day that catcher David Ross and right-hander Burke Badenhop elected free agency, Cherington said the team was still hopeful it could sign lefty Jon Lester.

''He's a free agent and obviously we know him well,'' Cherington said. ''We hope we get a chance to talk to him.''