The A's sent Matt Holliday to St. Louis on Friday in exchange for Brett Wallace, Shane Peterson and Clayton Mortensen.
The A's are also reportedly paying $1.5 million of Holliday's remaining salary.
Holliday, who not too long ago was supposed to be among the biggest names in this year's free-agent class, has hit .293 with 11 home runs and 55 RBIs this season. He went 4-for-5 in his first game with St. Louis, hitting cleanup behind Albert Pujols.
Derrick Goold reported that the Cardinals have not talked with Holliday about a possible extension.