Why do my draft picks say they are unused?

Unused draft picks represent a team's keepers.

For example, let's say your team has 20 roster spots with 20 keepers allowed, and you have currently have 16 keepers set. This leaves you with 4 available picks in the draft because you can only draft in as many rounds as needed to fill your roster. The other 16 picks will show in your draft pick list with a red highlight and the word "Unused." If you want to draft in 6 rounds, you will need to decrease the keepers you have set down to 14.