Clemente's Overzealous RompPDF Link. The article gives detailed account of only walk off inside the park grand slam in baseball history by baseball player, Roberto Clemente of baseball team, Pittsburgh Pirates on July 25, 1956. It states that Mr. Clemente overlooked the stop sign by his team manager, Booby Bragan and walked of from the field when he scored winning home run against baseball team, Chicago Cubs. It mentions views of baseball player, Jim Brosnan of Chicago Cubs and sports writer, Bruce Markusen on the events.| Massachusetts Review. Summer2015, Vol. 56 Issue 2, p249-255. | Literary Reference Center Plus (EBSCO) (Library Database)