Ultimate Mets Database Facebook page wrote: We received an e-mail from a fan asking how many Mets pitchers have hit grand slams. The answer is two: Carl Willey on July 15, 1963 and Jack Hamilton on May 20, 1967. Seven opposing pitchers have hit grand slams against the Mets: Art Mahaffey, Phillies, August 2, 1962; Burt Hooton, Cubs, September 16, 1972; Bob Gibson, Cardinals, July 26, 1973; Enrique Romo, Pirates, October 1, 1980; Dontrelle Willis, Marlins, July 7, 2006; Felix Hernandez, Mariners, June 23, 2008; Jason Marquis, Cubs, September 22, 2008.