[jhull]

Thinking of all the baseball applications here: catcher signals, third base coach, head coach etc.

[mkl]

Why would it be useful to have technology detect signals? Aren't people already going to be doing it?

Genuine question, I don't know how baseball works.

[ereyes01]

Hand signals are commonly used in baseball to surreptitiously communicate intent to teammates without giving away your strategy to opponents. I think what GP was getting at is that this technology could be used to automate the reading of hand signals. I'm not sure it would be effective, as the pro baseball players are already quite sophisticated at both reading and obfuscating hand signals, at least at the highest levels of the game.