It probably felt like a cutting-edge caper at the time: The New York Giants, using an elaborate spyglass-and-buzzer system, would have the opposing team's signs relayed from their center-field clubhouse at the Polo Grounds to the bullpen and then to the batter, passing along valuable information during the team's pursuit of the 1951 pennant.
The question nowadays is whether there's an app for that.
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Stealing signs is as much a part of baseball tradition as stealing bases, but the technology available now could open a whole new frontier of competitive sleuthing.