How many times do I have to explain this?
This was demonstrated by Kelly McKeown of the ASA office. He had two identical bats (and I think it was the Clarity). One had been rolled, the other had not.
The skin of the hand is too soft to feel the particulars of a bat (decals, graphics, whatever) under the coating. If you take a flexible, but rigid material (paper) and use that to feel the barrel, you can feel every bit of the design on the bat (other than that lasered). If you perform the same process on a portion of the barrel not cluttered with any designs or graphics and turn the bat in your hand with the paper, it should be smooth. When you have a very "busy" bat, one of the better places to check this is the neck just below the barrel.
If you hold the paper firm against the surface of the bat and turn the bat, if you can feel a constant series of ridges around the bat, something has been done to accelerate the breakdown period of the bat, most likely rolled. No one has ever said this applies to all bats, but it is an indicator the bat has been through the process of rolling.
This is what we were told, I'm not making it up on my own because prior to experiencing this paper process, I was under the belief that lacking external evidence, there was no way to determine if a bat had been rolled or vised.
My commissioner understandably held that same position. Then he secured a bat from a player who admittedly used a rolled bat, but only in non-ASA tournaments.
I showed him how to run the "test" against a non-rolled bat. He was stunned that he could feel the ridges on the rolled bat, but not on the other. Note: I'm not referring to a bump here or there, but obviously ridges equidistant around the bat.
As a matter of public dissemination, I had a few players/managers from teams waiting to play come over and each take a shot at the two bats. They were more shocked that there was a way to tell. Of course, the idea here was to get players gossiping about this and hopefully deter someone from taking a bat with the same technological science that can put a man into space and think they can improve upon it.
Now, I do not suggest that umpires arbitrarily go running around performing this test unless they have experienced the difference in a controlled environment as did those at the National UIC Clinic this year. However, I have no problem with those who know what to look for and where to find it to use this process on a questionable bat to take it out of play. That is a "questionable" bat that you have cause to suspect it, not every bat that seems to work well.