The right-hander signed a minor league deal in January after going 0-5 with 6.41 ERA in 12 games, eight of them starts, for the Seattle Mariners last season. Cardinals general manager John Mozeliak said Snell decided to quit before Tuesday's spring game against the Atlanta Braves.
The Cardinals had anticipated Snell starting the season at Triple-A Memphis.The move leaves them with 42 healthy players in camp.
"The initial hope was he was going to be someone who could give us protection at Memphis," Mozeliak said. "Someone is going to have to step up. It's not a huge hit to us at this point."
Snell pitched in one game, working two innings and allowing two runs on March 3. Since then he appeared in two "B" games, the last on Monday when he gave up two runs in an inning against Atlanta.
Snell is 38-53 with a 4.80 ERA in seven full seasons. He had a career-high 14 victories in 2006 and nine wins with a 3.76 ERA in '07, and was the Pirates' opening day starter in 2009.