I've discussed some simple hand signals before, but I want specifically to address verbal communication.
I don't remember defensive talk being a problem "back in the day." The coach told us to "talk on defense" and we talked. Times have changed.
Kevin Eastman has shared some of his thoughts about defensive talk:
- "Silent teams lose."
 - "Communication intimidates."
 - "Early, loud, and often."
 - Trust comes from communication.
 - Defenders in the back have to make the calls.
 
Eastman's mental aspects of defense are here, simply:
FOCUS, DISCIPLINE, RESOLVE = Concentrate, No Matter What, Every Time