He later played for the New York Gothams, and, due to his great stature, gave that team the enduring nickname "Giants". Connor hit baseball's first grand slam on September 10, 1881, at Riverfront Park in Rensselaer, New York. His grand slam came with two outs and his team down three runs in the bottom of the ninth inning, a situation known today as a walk-off home run. George Vecsey, in "The New York Times" wrote: "Roger Connor was a complete player — a deft first baseman and an agile base runner who hit 233 triples and stole 244 bases despite his size (6 feet 3 inches and 200 pounds)."