We've heard rumbles in recent seasons about major league teams engaging in technological sign stealing - using a centerfield camera or some skinny guy with binoculars hoisted into the scoreboard. A certain aroma of cheating naturally comes along with that, and righteous resentment. Fact is, stealing signs has always been part of the game, ever since signs were first used. But the deal is, you can't use equipment - you can only steal signs with your naked senses, is all. Players, coaches and benches can get very good at it, and games turn as a result.
Field coaches use all sorts of St. Vitus Dance to deliver signals to batters and baserunners. But spending your time trying to decipher their sign language - unless they're going with the most basic Little League belt for bunt, leg for steal - is a distracting waste of time. Better to watch the dugout, and the manager. Unless he's a great card player, he will tell you in a general way when something's up. If you wear shades and watch him peripherally, he can tell you a lot without spotting you spotting him. If he's calling pitches for the catcher, that can often be picked up visually and transmitted to hitters verbally or by sign, so they know what pitch is coming. But naturally, if he knows you're picking off his signs, he's gonna change them. So you have to pick his pocket without him feeling your hand. And your signs to your batter have to be equally subtle - the timing has to be right and quick and the reads accurate, else you'll just screw up your hitters. Not all batters want to know what's coming, and some are better off guessing or, better yet, just looking for their pitch to hit.
In college ball you see some complex and clever signing, and in the bigs it's an art form. College-level players will transmit signs for the coach from the bench, or from a corner of the dugout - verbally, or by pointing a bat in different directions or tossing/not tossing a ball. Taking off their hat. Calling your number or last name. Some teams keep up a barrage of number-calling to get on opponent's nerves, with most of the numbers - or all of them - meaning nothing. The coach might be giving signs but the hitter's getting the real ones from someone on the bench. Where someone is standing or what he's holding can put the same sign on or off. Teams build layers of signing that can be impossible to read without being obvious about it.
But more normally, signs are stolen and extra steps are taken. Just as bench activities can transmit signs, they can also read them. A good observer placed in the middle of a bunch on the bench can get a read and put an opposing system in place, tipping pitches to hitters or pending plays to infielders. Teams do learn to use stolen goods to great advantage, getting an extra step before what happens.
In the end it all gives way to execution - making the pitch, making the play, hitting the ball - and all the signs reduce to a pattern of wishes. Tactic and strategy only hold sway when the players can make the plays. And therein lies the resolute beauty of the game, which can't be stolen, but only returned.