Moore also announced the club had signed right-handers Brandon Duckworth and Zach Day to Minor League contracts and invited both to Spring Training.
If Riske is healthy, he gives the Royals another veteran right-hander with proven success at the Major League level. The 30-year-old has been one of the more reliable relievers in the American League since 2003, his first full season in the Majors.
Riske owns an 18-14 career mark with 16 saves and a 3.59 ERA in 328 Major League outings, all in relief, for the Indians (1999, 2001-2005), Red Sox (2006) and White Sox (2006). He has recorded nearly a strikeout per inning in his career (346 SO/361 1/3 IP) and has walked just 152. Opponents have hit just .229 against him in his career, including a .212 average by left-handed hitters.
He split last season between Boston and the White Sox, posting a 1-2 record and 3.89 ERA in 41 appearances. In 44 innings, his fewest since 2001, he allowed 19 earned runs on 40 hits and 17 walks while striking out 28. He missed most of April and May while with Boston, suffering from a lower back strain, and was traded to Chicago on June 15 for pitcher Javier Lopez. Riske recorded a 0-1 record and a 3.82 ERA in eight outings for the Red Sox and was 1-1 with a 3.93 ERA in 33 appearances for the White Sox.
"David has been one of the most consistent relief pitchers in the game the last four years," Moore said. "His experience and success will give us a better opportunity to match up the last three innings of the game."
Riske could serve as setup man to new closer Octavio Dotel. Todd Wellemeyer and Jimmy Gobble are among those also in the late-inning relief picture.
Moore has recently acquired several pitchers who could contribute in 2007, including several who are coming off injury-shortened seasons.
Since Oct. 10, Moore has acquired right-hander Ken Ray from Atlanta, signed free-agent right-handers Dotel and Gil Meche, acquired right-hander Brian Bannister from the Mets, picked up right-hander Joakim Soria from San Diego in the Rule 5 Draft, and now adds Riske, Day and Duckworth.
Day, 28, pitched for parts of the past five seasons in the Majors with the Expos, Nationals and Rockies.
Last season, he made just eight starts combined for the Rockies and Nationals before undergoing surgery on his right shoulder on June 6. The surgery, performed by Dr. Tim Kremchek, repaired a partial tear in his right rotator cuff. He was 2-5 with a 6.75 ERA last season, making three starts in Colorado and five in Washington.
The 6-foot-4 Day has a 21-27 career record with one save and a 4.66 ERA in 86 games, including 60 starts. After going 4-1 with a 3.62 ERA in 19 games (two starts) for Montreal in his 2002 debut season, Day was a mainstay in the Expos rotation in 2003 and 2004, combining for a 14-18 record and a 4.06 ERA in 42 starts.
In 2004, he recorded a 5-10 record despite posting a 3.93 ERA after receiving just 2.47 runs of support per nine innings, the lowest total in the Majors. An extreme groundball pitcher, Day's 2.25 groundball-to-flyball ratio since 2002 is the seventh-highest in the Majors.
Duckworth, 30, went 1-5 with a 6.11 ERA in 10 games, including eight starts, for the Royals in 2006 after being acquired from Pittsburgh for cash considerations on June 10. He fared better in his eight starts, recording a 4.85 ERA. Duckworth underwent season-ending surgery on Aug. 15 by Dr. Lewis Yocum in Los Angeles to remove bone chips from his right elbow.
Duckworth was designated for assignment by the Royals on Dec. 11 and became a free agent on Dec. 13 when he was non-tendered by the club.
Jim Molony is a writer for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.