Why are some players on my roster labeled as Can't Drop?

Owners can gain an unfair advantage by adding and immediately dropping players, preventing others from acquiring them until the following week.

You can prevent this behavior:

• Player that are added and released on the same day will remain free agents (bypassing the drop waiver requirement). Default after 2021.
• Lock recently-added players within 24 hours of the start of their game (or 48, depending on your league settings). Default prior to 2021.

To customize, go to League » Settings » Edit Waiver Wire Rules » Prevent Waiver Churning.