Claimed by the New York Giants on June 30, Schenz seemingly played no part in the 1951 Giants' furious late-season surge, when they won 37 of their last 44 games, including 20 of 23 at home, to overcome the Dodgers' mid-August 131⁄2-game lead, tie them at the close of the regular season, and defeat them in the final inning of the decisive third game of the 1951 National League tie-breaker series. He appeared in only eight games as a Giant, all as a pinch runner, and scored one run, on July 6.
However, a decade after the 1951 season, word began leaking out that the Giants' winning streak coincided with their adoption of using a telescopic spyglass to steal opposing catchers' signs from their center-field clubhouse at their home field, the Polo Grounds.[4] The spyglass belonged to Schenz, who had also employed it to steal signs for the Cubs and brought it with him to the Giants.[1] It was in use on October 3, 1951—allegedly operated by Giants coach Herman Franks—when Bobby Thomson hit one of the most dramatic home runs in baseball history: his "Shot Heard 'Round the World" that delivered a come-from-behind, walk-off, 5–4 triumph over the Dodgers and a National League pennant for the Giants.
The sign-stealing rumors began to gain credence in 1991, three years after Schenz' 1988 death, when one of the 1951 Giants, reserve catcher Sal Yvars, confirmed the accusation in The Home Run Heard Round the World, by Ray Robinson. Then, in January 2001, journalist Joshua Prager revealed details of the spying plot in The Wall Street Journal, and followed with a full account in his 2006 book The Echoing Green.[5] For his WSJ article, Prager interviewed 22 living players, including Thomson, who, although not denying that the Giants stole signs in 1951, said he ignored purloined intelligence when he batted (he found it distracting) and a stolen signal did not lead to his famous blast.[5] In addition, the Giants posted a 17–4 record in visiting ballparks during their remarkable skein, where Schenz' spyglass would have been harder to employ.