I remember how Vic Raschi, a member of the Yankees' legendary Big Three rotation, used to work with two regulation baseballs taped together. It was as much to strengthen his grip as it was to fine-tune his pitches. He didn't have an "Aunt Susie", which was what they called a curve ball then---but he didn't need it. He had an overpowering fast ball, an even deadlier slider, and a very good changeup, and I will never forget the first game of the 1950 World Series in which he pitched a 1-0, two-hit shutout and the poor Phillies put on a beautiful demonstration of how not to hit him. Yes indeed, the two baseballs taped together is a very useful tool.