A user may feel the need to change players, due to injury or performance, just like a coach on the field.
The system will track what point in the game the substitution was requested. You will retain the points earned by the original player, and will start earning points for the replacement player. The system tracks the game clock to ensure a user can not exceed the normal game time. For example, if you swap Player A when the game clock as 5:00 remaining in the first quarter, Player B will not start counting time until his game reaches 5:00 remaining in the first quarter, even if the game for Player B has not yet started.
If the replacement players game goes into overtime, the overtime stats will also be counted. However, you can not change to player if their game has already started overtime.
Your league can customize the Substitution settings based on your preference. It can be turned off completely, you can limit how many substitutions can be made during a week, or you can change how frequently substitutions can be made.