MLB players covering their mouths

When watching MLB I’ve noticed that when the catcher walks over to the pitcher to chat that they take their gloves and cover their mouths. I assume this is so someone watching with binoculars or watching tv who can read lips can’t decipher what they are saying and then pass it on to the opposing team.

Has this ever really happened that they now have to make this common practice? Has a team ever really had someone who is skilled enough in reading lips watch the pitcher/catcher discussions and then pass this info on to the opposing team dugout where they actually took advantage of it?

The way I’ve always heard it, you all have our Will Clark to thank.

A better cite

You will see the same thing done by NFL coaches in televised games – they use a clipboard to cover their mouth when they are talking on their radio, or to assistant coaches.

Seattle Mariners commercial about this topic.

I’ve heard it claimed–no cite, as this was heard during a game–that coaches have found that it also helps with the communication with either the guys upstairs or the QB.

I heard the same, that the microphones operate better when you cover them with the clipboard. Less crowd/sideline noise, I assume.