Ever have teammates ask the linecaller "So what's the play again?"?
My solution for the linecaller is to remember a sandwich:
Bread, meat, bread.
Or in this case:
Say the play, say who is doing what, then state the play again.
Example: "We are playing backhand clam for 4, transition into backhand man."
Then "George, break, Tim, mark, Ted, you are in the lane. Pete, middle middle, Greg, left wing, Albert right wing, John deep deep."
"So that's backhand clam for 4, people, backhand clam for 4 into backhand"
This way players can first visualise the play, then hear their position and know where they fit into it. Then hear the play again, because half of them will forget the count or the force, or weren't listening to your first four words.
The sandwich should mean fewer instances of people asking "so what's the force?", while taking minimal time to call the line.
The sandwich applies to offence as well. And don't forget to use a person's name - its the thing they listen to the most.