This may or may not be pertinent to the sign stealing discussion at hand, but....
While at JBP this year I was standing at the top of the runway directly behind home plate when I was asked by one of the ushers to move along. I gave him a quizzical look because there was no one around me at the time so I wasn't obstructing any pedestrian traffic and he pointed to a big open space in the wall of the stadium directly above and behind me.
"See that square opening up there?", he said. "That's got a fixed camera behind it and it and you can't stand in the way of it". I looked up and saw the opening and the camera and also saw two square objects mounted above and slightly to one side of the opening. One was gray and about four feet by four feet and the other was black and about eight feet by eight feet, about four times the size of the gray one.
"Ok", I asked him as I was moving to one side, "So what are those other two things?"
"Those two square things along with the camera record everything about every pitch" he said. "The positioning on the rubber, the body movement, the hand and arm position, the position of the grip on the ball, the arm slot, the spin rate, the type of pitch, the amount of break. Everything you can think of and some things you can't. That's cutting edge technology and our analytics department analyzes them after every game to work with the pitchers on their delivery."
If there's the technology to do that is there any doubt that any team can steal signs using a hidden center field camera?