I've worked up a page to allow a coach to change listed positions for players. The plan is to allow unlimited changing, but there is logic in place to limit the options for a player to positions that are reasonable given the player's ratings. Most players will be eligible for 3 positions, but some will be eligible for only 2 or possibly 4. I haven't seen a player be eligible for all 5 in my testing, but it's theoretically possible.
Can anyone think of problems that this will cause, or restrictions that need to be applied to it?