Our configuration - We have ALWAYS arranged our drive team like this:
Driver - Drives the robot, has control of the drivetrain only. This year, that included the actual drive motors, shifting, and movement of the arm for bump-crossing ONLY (all other arm movement was controlled by the operator). He/she generally has either two joysticks or a Logitech gamepad (not xbox - the xbox joysticks are not symetrical and do not work as well for a tank drive). He/She always looks at the robot only, focusing their attention on where they want the robot to go, what opponents are in their way, and how to get there. This year, they could pick which goal they wanted to go for based on which one was more open.
Operator - Handles the rest of the robot. They generally have a custom-made control box built for that robot, and might have another joystick also (for example, our 2006 robot had manual targeting on the joystick, while 2007 had slide/manual overrides on the joystick). He/She takes orders from the driver on mechanism operation, and adjusts parameters (such as kick distance) on their own.
human player - They generally operate “autonomously”, performing their tasks without interacting with the other drive team members too much. This year, the two goal human players would scream that the ball was in if the driver was pushing the ball up to the goal, so the driver knew to go away and get another.
Coach - This is always Jim Zondag. He looks at the entire field, and decides what the best plan of action is. He usually shouts orders (such as “GO GET THOSE BALLS ON YOUR LEFT AND SCORE THEM THEN GO HANG”). He does not care how the driver does it, just that the driver gets the balls and scores them as fast as possible.
After practice and events, they generally get very very good at communicating with one another. They know what the robot can do, how to perform their action fast, etc. I recently talked to our 2007 driver (Woody), who said that by the end of the season, him and Dave (the operator) knew how to drive and move the arm so that the whole robot would lean forward on the front two wheels and score at the same time, in one smooth motion.
Another important and related topic is how to choose the driver and operator. For us, we pick the driver and operator as a pair who work together well, and are dedicated to the team. They stay the latest on late nights, come every day, and generally try to hold leadership positions. IF the human player requires a certain skill (such as 2009), that will be a deciding factor. If the human player requires little skill (2008 robocoach, 2010, etc.) then the human player will usually be the one who shows promise as a future driver.