Here's the release from the Red Sox:
BOSTON, MA—The Boston Red Sox today signed right-handed pitcher Koji Uehara to a one-year contract through the 2013 season. In 37 relief appearances for the Texas Rangers last season, Uehara had a career-low 1.75 ERA (7 ER), ranking fifth among American Leaguers with at least 30.0 innings. He also posted the third-highest strikeout-to-walk ratio (14.33) and the fourth-lowest WHIP (0.64) in modern Major League history (since 1900).
Uehara (pronounced EW-eh-hara), 37, recorded 43 strikeouts compared to three walks over 36.0 innings in 2012. His 14.33 strikeout-to-walk ratio trailed only Hall of Famer Dennis Eckersley (18.33 in 1989, 18.25 in 1990) among all-time single-season leaders.
He held right-handed batters to a .125 average (7-for-56) last season, the fourth-lowest mark among Major Leaguers with at least 50 batters faced. Among AL pitchers against right-handed hitters, he also ranked tied for second in opponent OPS (.369) and sixth in opponent slugging (.214).
Following a 10-year career in Japan, Uehara was signed as an international free agent by the Orioles in 2009 and made 12 starts that year. Since shifting to the bullpen in 2010, he leads all Major Leaguers with a 10.76 strikeout-to-walk ratio (183 K/17 BB) and has averaged 11.36 strikeouts per nine innings (145.0 IP), the third-highest mark among American Leaguers with at least 125.0 innings over that time.
Over the last three years, he has held right-handers to a .177 batting average (47-for-265), third in the AL during that time (minimum of 200 batters faced). He posted a 0.72 WHIP or lower in consecutive seasons (0.72 in 2011, 0.64 in 2012), becoming just the second big leaguer ever to accomplish the feat along with Eckersley in 1989 and 1990.
The Osaka, Japan native, who was traded to the Texas Rangers on July 31, 2011, is 5-9 with 14 saves, 35 holds, and a 2.89 ERA (68 ER/211.2 IP) while striking out 231 compared to 29 walks in 157 appearances over four Major League seasons with the Orioles (2009-11) and the Rangers (2011-12). Among Japanese-born pitchers in the Majors, his 0.92 career WHIP and 1.23 walks per nine innings are the lowest such rates ever, while his 9.82 strikeouts per nine innings is second all time to Takashi Saito (minimum of 200.0 IP).
He appeared in three postseason games for the Rangers in 2011 and tossed a scoreless frame for Texas in the 2012 American League Wild Card game.
In his 10 seasons (1999-2008) for the Yomiuri Giants in the Nippon Professional Baseball (NPB) Central League, Uehara compiled a 112-62 record with 33 saves, a 3.01 ERA (518 ER/1,549.0 IP) and 1,376 strikeouts. He led the NPB in wins in 1999 and 2002, ERA in 1999 and 2004, and strikeouts in 1999 and 2003.
An eight-time NPB All-Star (1999-2005, 2007), he was named the Central League Rookie of the Year in 1999, along with winning the Sawamura Award as the NPB’s top pitcher, the Golden Glove Award, and being named to the Top Nine Award as NPB’s best all-around starting pitcher in both 1999 and 2002. He led the Giants to the Japan Series championship in 2000 and 2002.
He also participated in both the 2004 and 2008 Olympic Games for Team Japan, and helped lead his country to the gold medal at the inaugural World Baseball Classic in 2006.
Uehara will wear No. 19. With the signing, the Red Sox 40-man roster is now at 40.