Casey, a career .304 hitter, is expected to provide much-needed offense from the left side as the Tigers try for their first postseason appearance since 1987 and their first winning record since 1993.
"We like Sean Casey a great deal," Tigers president Dave Dombrowski said. "He's a solid major-league hitter and he's solid at first base. He makes us a little better right now."
To make room for Casey on the roster and in the lineup, Detroit optioned first baseman Chris Shelton to Triple-A Toledo. Shelton is
hitting .277 with 16 home runs and 45 RBI.
Shelton had a spectacular April, hitting .326 with 10 homers and a franchise-record 19 extra-base hits, but is hitting .260 since then with six homers -- and he is striking out more than once every four at-bats.
"We like Chris, but he's been scuffling," Dombrowski said. "We thought it would benefit him to go back to Triple-A, and when we talked to him today, he didn't disagree. He'll be back with us sometime this year."
Detroit manager Jim Leyland called Shelton the Tigers' "first baseman of the future."
"He played an outstanding first base," Leyland said Monday before the Tigers played the Tampa Bay Devil Rays in Florida. "He played a very important part in where we've gotten. He carried us offensively for a month and a half.
"It's just one of those situations where Chris Shelton needs to go down and play," Leyland said. "I think he'll be our first baseman next year, and maybe more this year again."
While Casey does not have Shelton's power -- the 32-year-old has just three home runs and 18 extra-base hits this season -- he will immediately become one of the most patient hitters in Detroit's batting order. His .377 on-base percentage this season ranks second among the Tigers behind Carlos Guillen's .384.
Leyland said he hadn't decided where Casey will bat in the lineup.
"I haven't thought about it, to be honest with you,'' Leyland said. "I won't think about it until I go home tonight."
Casey also gives the Tigers a defensive upgrade over Shelton, a converted catcher. Shelton made a key error in Sunday's 6-4 loss to the Twins, while Casey is a career .995 fielder and has not had an error this year.
Casey, a three-time All-Star, missed six weeks with two fractures in his lower back after being hurt April 14 and sat out Pittsburgh's last two games with a strained right ribcage muscle.
Casey grew up in Pittsburgh and is looking forward to playing for Leyland, who began managing the Pirates when Casey was a youngster.
Casey was the Pirates' highest-paid player at $8.5 million, with the Reds picking up $1 million of his salary. The Pirates traded left-hander Dave Williams to the Reds for Casey during the offseason but later chose not to attempt to sign Casey to a multiyear contract. Casey is signed through this season.
The first baseman spent most of his career with the Reds, driving in 85 or more runs in four of his seven full seasons in Cincinnati. He was a such a popular player while in Cincinnati that he was given the nickname "The Mayor."
Rogers, considered a fringe prospect, was 3-2 with a 2.39 ERA in 37 appearances at Double-A Erie this season. A 11th-round draft pick in 2003, he moved into the bullpen last season after previously being a starter.
Dombrowski said the Tigers were never close to making a major deal, saying talks with Washington over Alfonso Soriano fell apart over Detroit's best prospect, outfielder Cameron Maybin.
"We inquired about Soriano, but it was one that never went anywhere," he said. "They asked for Cameron Maybin to be part of packages of players. I said I wouldn't trade Cameron Maybin straight up for Alfonso Soriano, so we were never close."