"We are pleased to add a quality veteran player like Derrek Lee to our ballclub," general manager Neal Huntington said in a statement. "He is an experienced, productive right-handed hitter and solid defender who should add to our team on the field and in the clubhouse."
While Lee, who was a two-time All-Star with the Cubs, hasn't put up stellar numbers this season, his arrival should improve the Pirates' production at first base. He'll become the team's new everyday first baseman over Lyle Overbay, who could end up being released by the club.
If the Pirates release Overbay, they would still be on the hook to cover the rest of his $5 million salary. The Pirates will make a move to open a spot on the 25-man roster when Lee arrives.
In 85 games with the Orioles this season, Lee hit .246 with 15 doubles, 12 homers and 41 RBIs. He missed some time earlier in the summer with a left oblique strain.
Lee's production has been much better in recent weeks. In his last 18 games, he has batted .309 with 11 extra-base hits and 16 RBIs. He has hit .294 since June 17 and has been a better second-half performer throughout his career.
"It's the business of baseball," Lee said when asked about being traded midseason for the second time in two years. "[The Pirates] are playing good. They turned it around, so good for them."
Overbay has not been able to get out of an offensive funk all season. He is hitting .220 this month and .227 in 102 games this season. The Pirates went after both Overbay and Lee this offseason when looking for a first baseman.
Lee, 35, eventually signed a one-year deal with the Orioles worth $7.25 million. The Pirates would have to pay the remainder of that salary.
Though manager Clint Hurdle couldn't speak specifically on the trade immediately after the Pirates' 7-4 loss to the Phillies, he did say he would welcome an addition on offense. Lee, in particular, would be able to slot into the middle of a Pirates lineup that is lacking behind Andrew McCutchen and Neil Walker.
"I think one [bat] would help," Hurdle said. "It could make a difference. It stretches your lineup out."
Lee became expendable to the Orioles after they acquired first baseman Chris Davis in a trade with the Rangers earlier in the day. With Baltimore currently playing in New York, Lee will likely be in uniform with the Pirates for Sunday's series finale against the Phillies. The club moved Ryan Doumit to the 60-day disabled list to clear room on the 40-man roster for Lee.
As the Pirates look to upgrade before Sunday's 4 p.m. ET non-waiver Trade Deadline, they have been hesitant to give up too much in the way of prospects. They avoided doing so with this deal. Drafted in the 11th round in 2009, Baker hit .282 with 15 homers and 73 RBIs in 103 games for Bradenton this season.
Jenifer Langosch is a reporter for MLB.com. Read her blog, By Gosh, It's Langosch, and follow her on Twitter @LangoschMLB. This story was not subject to the approval of Major League Baseball or its clubs.