Rotation is often misused, or misunderstood. The term is correctly used as a degree measurement of the amount the axis is rotated from 0 degrees ( pure end over end ) to 90 degrees ( maximum side roll ). People sometimes confuse the term with rev rate, which is independent from axis rotation. You can have a high rev rate with low axis rotation, or a low rev rate with high axis rotation.
The current trend among the best bowlers who see lots of flatter conditions is to maximize their rev rate while reducing their axis rotation.