Kennedy, 33, batted .280 with a .321 on-base percentage and .372 slugging percentage in 2008. He saw his playing time dwindle as the 2008 season went on and requested a trade late in the year. Unable to work out a deal, the Cards held onto Kennedy until Monday.
"I tried to exhaust the trade market," general manager John Mozeliak said. "We thought we might have something happening that really came to an end this weekend. At that point it was just time. It was more fair for both parties to do it now than wait a couple weeks."
With Kennedy gone, the Cardinals have no clear-cut favorite to man second base in 2009. Among the candidates for playing time are Brendan Ryan, Brian Barden, Joe Thurston and possibly outfielder Skip Schumaker, who will be working out at second base this spring.
Mozeliak said that for the time being, the Cardinals expect to go with an in-house option at the keystone corner. Several veteran second basemen remain unsigned in the free-agent market, including Orlando Hudson, Ray Durham and former Cardinals player Mark Grudzielanek.
"Right now, we're going to go with what we have," Mozeliak said. "We would like to do this internally if we could, and we do have confidence that we can."
One side effect of the move is that if Schumaker shows viability at second base, Kennedy's departure could help clear the way for top prospect Colby Rasmus to make the Opening Day roster.
According to Mozeliak, manager Tony La Russa was consulted in the discussions as to what to do with Kennedy, and was on board with the decision to release Kennedy. The general manager acknowledged that one element in the move was the desire to make sure that everyone on the roster is pulling in the same direction.
"It was something that Tony and I have talked about the last few weeks in trying to put our best foot forward with our team," Mozeliak said.
"I do think this was an opportunity to inject some energy into that position and really show that we are moving this club in a newer direction."