The list of players who have helped their stock and greatly increased their draft position/earnings because they had a good 3 or 4 days is long and extensive. Yes, some have hurt their stock too, but much more often than not it's the positives that are carried over from down there as opposed to negatives. It can often be a red flag that has to be managed well by the reps when an invited player declines to participate (unless it is someone that is a sure fire 1st round type guy).