The New Balls CanardSports commentators have remarkable confidence in some of their assertions (almost like business reporters). During today's coverage of the Rogers Cup Verdasco-Roddick match, the fact that Roddick is serving with new balls is cited as a great advantage.
I recall Paul Kedrovsky blogging about this, as I have often wondered about it.
The funny thing is, that seemingly isn't true. According to Wimbledon data analyzed by a pair of economists with a fondness for tennis arcana, first serve points are no more likely with new tennis balls than old ones. If anything, double-faults are more likely, implying it may be better to serve using older balls than newer ones.