Well I checked the website and it definately said the arrow should not be tight in there. However, I think the setup we have now is either the Large or Extra-Large and the biggest carbon arrows should be Medium with some being Small. Either way, it doesn't make TONS of sense they are so erratic because there are drop away rests and the like, where the arrow just rests on something.

Either way, the arrow is resting on something in the whisker biscuit regardless of size.