Today's New York Post had an article describing Carlos Beltran "methodically wiping a rag over the barrel of his bats. He was cleaning off the marks made by previous batted balls". Beltran said that "It's something I just like to do. I like to wipe off the bad marks and leave the good ones".

Now there's something that doesn't exactly help in photomatching!

How widespread is this practice among players? Has Beltran always done this?