Bob Sheppard, the public-address announcer for the Yankees since 1951, is retiring, according to Paul Doherty, a friend and agent who has represented Sheppard. Doherty said that Sheppard?s son, Paul, told him about Sheppard?s plans on Wednesday morning. ?I think Bob just wants to take it easy and no longer have the pressure of, ?Can he? Will he? Or won?t he??? Doherty said in an e-mail message. ?And, at 98, who can blame him?? Sheppard, when asked to confirm that he was officially retiring, said, ?I never said it.? ?Now on to him seeing his 100th birthday in a year and a half,? Doherty said. The Yankees have not named a replacement for Sheppard, but it will not be Jim Hall, Sheppard?s longtime backup. Paul Olden will fill in for the two exhibition games at the Stadium this weekend.