Re: Aaron Donald training...lol insane!!

My guess is this:

The knives extend reach thus meaning Donald has to be quicker to avoid getting touched by them. Also that extended reach means he has to get inside quicker as well. If he was not fast enough he would hit the outside of the knives and thus fail the drill. I am not sure if this is it or not and there might be more reasons as well, but this was all I could think of.