The "Core Four" is down to two. New York Yankees catcher Jorge Posada is planning to retire, a source told ESPN The Magazine's Buster Olney. The source told Olney that Posada, 40, is trying to determine the right time to make an announcement, which is expected to be in the next two weeks. Posada, shortstop Derek Jeter, closer Mariano Rivera and left-handed pitcher Andy Pettitte compiled the core group that helped the Yankees win five World Series championships between 1996-2009. Pettitte retired after the 2010 season. Read more: http://espn.go.com/new-york/mlb/sto...cher-jorge-posada-planning-retire-source-says
