For this entire discussion it is assumed that the team starts with the DP/Flex option.

To better understand the DP/Flex rule, you must understand these basic concepts:

o The DP and Flex are spots in the lineup card, occupied at at specific time by a player.
o Do not confuse the DP spot with the player who is acting currently as the DP.
o Do not confuse the Flex spot with the player who is acting currently as the Flex.
o The DP spot can never be empty; it is part of the batting order and aplayer must occupy that spot.
o The Flex spot can be temporarily empty when the Flex player is not playing defense.
o If the Flex spot is empty, it can always be re-filled with player.

If the DP player or Flex player is out of the game at any point in time, a team may put a substitute into the DP spot or Flex spot in the lineup without having to reenter the original DP player or Flex player who is currently out of the game.

Substitution rule: The DP and Flex are charged with a substitution when they are not doing what they are designed to in the lineup.  When the DP is out of the batting order or the Flex is not playing defense, they will be charged with a substitution.

Examples

1. Flex player runs in the DP spot. End of inning. Coach says he wants to reenter the DP player. You must ask if he intends to put the Flex player back to the Flex spot and go back to 10 players, or reenter the orginal DP player without putting the Flex player back to the Flex spot, staying at 9 players.
In the above example if the team wants to go back to 10 players, the logical way of thinking about this is to first move the Flex player back to the Flex spot. The DP spot may seem to be temporarily empty but it cannot be. Now either the original DP player or a substitue may be put into that DP spot.
In the above example if the team want to stay at 9 players, the Flex spot is now empty. The Flex spot may be filled any time later in the game with either the original Flex player or a substitute.

2. Flex player runs in the DP spot. Coach wants to go back to 10 players and put a substitute into the DP spot. This is legal. The original DP player has not used her re-entry.

3. DP player plays defense for the Flex player, so the Flex spot is now empty. Later in the game the team wants to go back to 10 players by putting a substitute into the Flex plot. This is legal. The original Flex player has not used her re-entry.