On May 20, 2008 — Mike Piazza announces his retirement. A 12-time All-Star, Piazza hit .308/.377/.545 in 16 seasons after having been picked in the 62nd round of the amateur draft. He socked 427 home runs, scored 1,048 runs and drove in 1,335 and set the all-time major league record for homers by a catcher. At the time of his retirement, Piazza is 30th in history in slugging, 39th in home runs and 64th in OPS+. Many opine that he is the greatest catcher ever, though others argue the claim, citing Josh Gibson or others.

Source:
Baseball Reference May 20