So it's a big game of whack a mole? I think someone else would notice guys' heads popping up and down depending on the pitch. Actually, it's not impossible. The dugout is angled so it's really hard to look at the game and the scoreboard at the same time (and you can't see the catcher's signs in the first place). So unless the manager/pitching coach are feeding signs to the catcher (which seems rare these days), they're not going to know what pitch is coming. All the members of the other team except the catcher are facing home plate. The catcher has to watch for the ball coming from the pitcher (ditto the ump). The crowd is focused on 1) the infield diamond and 2) talking to each other. If they are looking at the outfield scoreboard it'd be the ball/strike count. If you want to go even more "crackpot" conspiracy theory, since the Cubs own WGN and CSN, they could tip off the production crew not to film the scoreboard during the at-bats. Well there's a half dozen or so guys in the bullpen and another dozen or so in the dugout. It would be incredibly easy for them to track a guy moving in the scoreboard on every pitch. You take 2 guys in the dugout, 1 of them notes what the operators are doing, the other tracks the pitch. If they are standing still during consecutive fastballs then moving when it goes fastball, offspeed, breaking pitch, you can start theorizing. Plus, doesn't the opposing teams production staff have access to whatever camera angles they want?