It's harder earlier in the day, but towards the end its pretty easy to show numerical data and say "No, you cannot do what you are saying you can" and present your numbers. There have been situations where people are adamant that they can still perform the task and it loses you the match.
I Try to find compromise and say: "Our numbers say you cant do that at all, but that you're really good at this. Execute this well and you will definitely get picked for an alliance come elimination."
Remember, numbers never lie
