The Rangers also get $2 million back from the Orioles, according to sources.
Uehara, who has closer experience, is making $3 million this season on a contract that includes a vesting option for $4 million in 2012 if Uehara pitches in 55 games. He's already appeared in 43, so it looks likely that option would kick in barring injury.
"Koji is one of the most effective relievers in the game this year and last year," Rangers GM Jon Daniels said. "He's battle-tested. He's done it in the AL East. He's a strike-thrower and has the ability to make guys swing and miss. We're excited to have him."
Daniels said the trade doesn't have to proclude them from adding another bullpen piece, but that it "takes the edge off." The club doesn't have anything imminent and Daniels said he doesn't expect to do anything else "certainly not tonight, but who knows about tomorrow?" The deadline ends at 3 p.m. Dallas time.
Hunter said he was shocked and surprised to be dealt. But he hopes to become a solid rotation member for the Orioles.
"I'm a starting pitcher. I'm not a bullpen guy," Hunter said. "I'll be back in a position to where I'm pretty comfortable."
Hunter is excited to work with former Rangers pitching coach Rick Adair, who is in Baltimore now.
Uehara is 1-1 with a 1.72 ERA in 47 innings with the Orioles this season. He has 62 strikeouts to only eight walks in that span. The right-hander has held left-handed batters to a .146 average, while righties aren't doing much better at .171.
He has similar numbers home and away with his ERA higher on the road at 1.80 (it's 1.67 at Camden Yards), but opponents are batting just .155 against him on the road (.151 at home).
Uehara had 13 saves in 2010 despite a two-month stint on the disabled list, so he can close games if needed.
He has thrown 7 1/3 innings against the Rangers' AL West opponents this season and has allowed one run on three hits with nine strikeouts and no walks. He hasn't faced the Rangers in 2011.
Davis, 25, was the club's fifth round pick in 2006. He's consistently hit at Triple-A, but hasn't been able to translate it consistently at the big league level.
Davis said he had mixed feelings about the trade. He said he'll miss his teammates and coaches, but added that he needs a fresh start.
"The biggest thing is not playing every day is really hard for a guy who's always been an every-day player and a power hitter," Davis said. "When you're a power hitter you rely on timing and rhythm to get you locked in. It was tough playing three or four games and sitting. Today was a great example. I got four at-bats and it took me some time to get comfortable. That's a big thing for me. Especially being such a young player, it's critical for me to be in there every day and hit every day."
Hunter, who turned 25 earlier this month, was taken in the supplemental first round by the Rangers in 2007 (54th overall). He was 13-4 with a 3.73 ERA in 23 games (22 starts) for the Rangers in 2010 and was expected to start the season in the rotation until a strained groin forced him to the disabled list. By the time he returned, the Rangers' rotation was set and Hunter was pitching out of the bullpen. He is 1-1 with a 2.93 ERA in 15 1/3 innings this season with the Rangers.
Richard Durrett covers the Rangers for ESPNDallas.com.