ASA refers to it as Advanced Break in Technology (ABT) and it is illegal. Somewhere on the web is a good explanation from ASA on bat tampering.I have done my share of reading up on rolling bats, what it does, etc. Normally it takes a couple hundred hits using a composite bat to break it in, and to get its full potential out of them. Rolling a bat does nothing more than hitting a couple hundred balls does, it just breaks the bat in right away. Same as hitting with it, rolling puts pressure on the bat, causing micro fractures in the composite material, giving it the "trampoline" effect, making it more active right away. Hitting softballs does the same thing, just takes longer. It makes it no more dangerous than breaking it in during batting practice. It does not alter the bat anymore than batting practice either. There are tons of arguments on if it is legal or not. I know you can not alter a bat, which rolling does not do. I do not agree that it is cheating eiother since you arent adding anything to the bat or taking anything from it, such as shaving it. You will get a ton of opinions on this subject. I guarantee there are alot of rolled bats out there. You wouldnt be able to tell the difference from them or the bats broken in from batting. This is a pretty hotly discussed subject on message boards to. Everyone has their own arguments about it. My opinion is, I dont think it is bad if someone rolls their bat, since it does not change the composition of the bat and since it does nothing more than batting practice, hitting a couple hundred balls does. Now shaving a bat to change it physically and give it alot more juice than it normally could be, that I dont agree with and would be against it.