I've always been the primary driver, and my team has never rotated me out. We also have a master strategist (student mentor) that got us through VCU who is always in the operator station because he knows the 'bots we're up against and yells me tips during the round.
Our human player and secondary driver get to rotate - there are 3 or 4 human players that can take up the position rather successfully, and our secondary driver only has two buttons, the goal grabber in/out and the compressor cycling off/on. They're not allowed to touch the compressor cycling button
So yeah, the only real position that rotates throughout the entire team is the secondary driver. Note, however, that we only employ students in our drive team (no adult mentors).