What is a mock draft in fantasy football?
A mock draft is a practice draft that doesn't count for anything, run to rehearse strategy, learn ADP, and prepare for your real draft.
A mock draft simulates a real draft — against other people or computer opponents — so you can test strategies and see where players go without any consequences.
Running several mocks from your real draft slot teaches you which players tend to be available in each round, so on draft day you know whether to grab a position now or wait. Mocks are also where ADP data comes from: enough drafts aggregated together produce each player's average draft position.
The more mocks you run, the more comfortable you'll be reacting to runs on positions and unexpected falls. Treat them as reps — the goal is preparation, not the practice 'result.'