Down cold

"Great communicators have their leads down cold."
What does "have something down cold" mean here? Thanks!

They know it completely and totally and can deliver the message perfectly.

From Merriam-Webster:

c : marked by sure familiarity : Pat had her lines cold weeks before opening night.

Down cold, or down pat I understand. I'm not sure about leads. Is that like "lead-in"? Introductory phrase? First joke? SS