I was under the impression you do NOT talk to your team mate, in any verbal or non verbal means while he's in the match unless you call a coach or the other team calls a coach.
"hey, lets go Rich might be code for "play safe", where as "Lets go Richie" might be code for shoot the ball, and "Lets go Richard" might be code for I think I have a great idea but don't want to burn a coach if you are thinking what I'm thinking. So, if not, call me over, I think I have a WINNER idea.
In many many baseball leagues, once the pitcher looks for the signs from the catcher, the team up to bat cannot no longer cheer for the batter in any manner as they could be giving him signs of what pitch is coming. And yes, it's happened many times. Lets's go #22 could mean fastball, Let's go Billy is curveball, Let's go William is chang up, etc.....
Silly that it has come to this, but there are always teams that ruin it for others.
Plus, SILENCE is GOLDEN. Many NFL teams have done away with cheerleaders, do pool players need this option