Timlin, 34, had served as the Orioles' closer since joining the team as a free agent after the 1998 season. He's 4-for-4 in save opportunities since July 7 and has 11 saves in 15 chances this year.
He likely will serve as a setup man for David Veres, who has 18 saves.
"Obviously it's a good thing to be going from fourth place to first place," Timlin said. "St. Louis is one of the places I almost went before I signed here."
For the Orioles, the trade emphasized the team's sudden willingness to unload veterans for youth. Baltimore traded 34-year-old shortstop Mike Bordick to the New York Mets on Friday for shortstop Melvin Mora and three minor leaguers.
Timlin, 2-3 with a 4.89 ERA in 37 relief appearances, is making $4 million in the second season of a $16 million, four-year contract that calls for him to get $4 million next year and $5 million in 2002. As part of the deal, Baltimore will pay part of the remainder of the contract.
"I expect Mike to have great success with St. Louis," said Syd Thrift, the Orioles vice president of player personnel.
Timlin experienced mixed success in Baltimore. He blew eight save chances in the first half last year before going 18-for-19 in the second half. This season, the fans booed him after an ineffective stretch that temporarily cost him the role as the Orioles' lone closer.
"I took a lot of ragging, but being a reliever, you're going to get that. You deal with it," he said.
He plans to join the Cardinals in New York on Sunday for their game against the Mets.
"I'll get to say hi to Mr. Bordick, then we'll just take it from there," Timlin said.
Richard, 26, was recalled by St. Louis on July 17. He made his major league debut that night and became the 80th player ever to homer in his first at bat when he connected off Minnesota's Mike Lincoln.
"I saw there was a need for the team in the future. He was a top priority for us," Thrift said.
Richard was 2-for-16 in six games with the Cardinals after batting .277 with 24 doubles, 16 home runs and 75 RBI in 95 games for Triple-A Memphis. He went 2-for-3 with an RBI and a run scored in the Triple-A All-Star game on July 12.
Last year, he batted a combined .298 with 30 home runs and 98 RBIs between Double-A Arkansas and Triple-A Memphis.
Nussbeck, 26, was 9-4 with a 3.96 ERA in 21 starts for Triple-A Memphis. He allowed 127 hits in 125 innings, walking 44 and striking out 76.
Nussbeck was the Cardinals' 29th-round selection in the 1996 amateur draft. He was assigned to Triple-A Rochester.
"He's a starting pitcher, so we're happy with that transaction," Thrift said.
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