writes "R.A. Dickey, pitcher for the New York Mets, has been in the news this week after two dominant pitching performances in a row, holding opponents to one hit in each of the games for the first time since Dave Stieb did it in 1988. He has taken over as the league's only knuckleball pitcher after Tim Wakefield retired last season. But just what is it about the knuckleball that makes it hard to hit? Conventional wisdom has it that the lack of spin on the knuckleball causes it to move in completely unpredictable ways, even changing directions in mid-flight. In the last few years, there has been a lot of good science done to understand baseball pitch trajectories, and a few months ago Prof. Alan M. Nathan showed that knuckleballs aren't really so different from other pitches. It turns out that the same 9-parameter equation that can be used to describe other pitch trajectories applies just as well to the knuckleball. The difference appears to be that, like in a chaotic system, knuckleballs depend sensitively on the initial conditions, so that small changes can cause randomly different forces at the start of the pitch which determine the resultant trajectory. Much of this and similar work depends on the Pitchf/x tool, which has recorded the complete trajectory, spin angle and spin rate of every MLB pitch since 2007! Baseball really does have the best sports stats geeks."