[AtlUmpSteve]

Let me add a teaching tool I have used to help explain the concept. Assume there are actually 10 defensive positions; and the DP is playing "bench". You can have the LF and RF switch defensive positions, and we know they still bat in the same order, and neither has left the game. Use the same concept, and the SS and "bench" can switch defensive positions, and neither has left the game.

If you think along that concept, you then only need to add the FLEX is married/twinned to the DP spot in the batting order, NOT to the person playing the defensive position of "bench", no matter who that is any any given time.

While I know you say you understood, I hope others can take something from this way of explaining the concept.