Both Patterson and Hairston are among a large pool of experienced free agents that remained unsigned with big league camps in full swing.
In the early days of camp, Reds manager Dusty Baker talked about wanting someone like Patterson or free agent Kenny Lofton to be signed as a potential leadoff hitter.
Patterson played for the Cubs from 2000-05, including two years under Baker. He spent the last two seasons with the Orioles.
Patterson's lifetime .298 on-base percentage doesn't indicate he'd be an ideal leadoff hitter, however. But once he gets on base, the 28-year-old can be dangerous. He stole 37 bases last season and 45 in 2006.
Last season in 132 games, Patterson batted .269 with eight home runs, 45 RBIs and a .304 OBP. Although he batted .235 in the first half, he rallied to bat .313 after the All-Star break.
Krivsky said it would be up to Baker how Patterson might be used in a lineup.
Lofton was seeking a big league contract but a deal didn't come together with the Reds' 40-man roster full. Patterson will join Norris Hopper, Ryan Freel and top prospect Jay Bruce to battle for the vacant starting spot in center.
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The Patterson signing could put a dent in Bruce's chances. The 20-year-old is currently day-to-day with a mildly strained left quadriceps muscle.
"It just adds to the competition we have," Krivsky said. "It's a chance to compete, that's all. There are no guarantees for either one."
Hairston is a lifetime .253 hitter that spent 1998-2004 with the Orioles. He also played for Baker in Chicago in 2005-06. In 73 games last season with the Rangers, the 31-year-old batted .189 with three homers and 16 RBIs.
"He has experience at second base, shortstop, third base and all three outfield positions," Krivsky said. "He's just another versatile guy for our bench that could do several things to help us win a game."
Patterson, who lives in Atlanta, was expected to be in camp on Tuesday morning but not play in the afternoon game vs. the Indians. Hairston is scheduled to fly to town from Arizona and arrive at the Reds' complex some time during the day.