You're not supposed to convey the signs to the current hitters. It’s to look at movement, location, release point, swings, etc.
With that said it is a system begging yo be abused, so all the self-righteous hand wringing is pretty absurd. In this day and age of marble-sized high definition cameras no sign is safe, especially if it's legally being pumped into the clubhouse.
No way teams aren't finding ways to steal signs, especially at home.
IMO the whole Astros scandal is more ridiculous than deflategate. Which is saying something. Manfred wouldn't have done anything at all except the media predictably freaked out with an avalanche of moral outrage.