I didn't see it this year, but there were two separate sessions on bats and equipment testing; it could have been demonstrated in the other. But, I did see it in detail and practice at the Clinic two years ago (2009).

In the most simple terms, breaking in a bat by hitting balls creates fibers to break/compress in small spots at a time. There would never be a uniform pattern that can be discerned if this legal method is used.

But, when rolling a bat, to accelerate the break-in period, the bat rollers compress lines or planes at a time. This creates waves, patterns that can be identified when running your hand down a bat, just as we (assume you have been taught to) do when looking for dents or other imperfections. I have always done that with metal bats, but not composite bats (since they don't dent), until I understood the rolling process.

The sensory perception is magnified in your hand if/when you hold a single sheet of paper in it, and feel the bat slide through your hand through that sheet. Slide the bat from the taper to the end, then back up while turning it to feel all sides at each location along the barrel. If the bat has been rolled, you will normally feel the waves or patterns.

This can only be counteracted by a bat "roller" spending hours, days, even weeks, to compress spots individually, rather than sections at a time. As a rule, that simply doesn't represent the amount of time they are willing to spend for a return on their time investment.

I was lucky enough to perform this in 2009 with Kelly McK and it was really amazing how that piece of paper adds to the sense of feeling.

It does not guarantee that you will catch a rolled bat in this manner, but there is a discernable set of ridges you can feel with that paper. Having been challenged locally and performed for commissioner and players. They provided the bats without any knowledge to me which was rolled.

They were shocked that I got it right, but insisted on carrying the player's denial that it wasn't possible and I got lucky.

It should be noted that it provides such a delicate sense that you can feel the decals under the coating, so I recommend it be done on the taper were there rarely decals of any type.

Is that so? What's the difference between obstruction and interference, bot? :p