He told general manager Jim Hendry that he didn't see the progress he wanted to at this point, and he decided to ask for his release.
"B.J. was tremendously professional and told us that right now he didn't feel he would be helping himself or us at this point, and asked for release," Hendry said.
Ryan Theriot needs a couple days off after getting hit in the arm during Tuesday's game. Aaron Miles, who was called up earlier in the day, will start at shortstop Wednesday against the Cincinnati Reds.