Gary Sheffield asked the Mets for a contract extension, the club rejected the overture and now Sheffield has threatened to leave the team and head home, two sources told the Post. As of 6:30 p.m., one of the sources said, Mets officials and Sheffield were in discussions on how to move forward. Mets pitcher Tim Redding actually said he heard Sheffield had been released. But a Mets official told the Post that was inaccurate and that Sheffield had not been released.