ESPN wrote:Sheffield was replaced on the active roster by outfielder Kevin Thompson. Thompson hit .383 for New York in spring training, and was hitting .288 in 36 games for Triple-A Columbus.
Same article says Mo Riv tweaked his back...
I'm not celebrating Sheff's injury btw, which really sucks, but I'm happy to see a guy I think could be a solid contributor a la Melky. Could be a move for the future.