Scott Tobias highlights a new documentary, Knuckleball!, about Tim Wakefield and R.A. Dickey – Major League Baseball's only pitchers last season to deploy the offbeat weapon:

There are essentially two things that can happen with a knuckleball. It can float toward the plate without spin, jerk around like boozy relatives at a wedding hall and make the world's best hitters look like hapless Looney Tunes characters. Or it can float toward the plate with spin, lope with a steady trajectory at 65 mph and give the world's best hitters the juiciest slab of red meat this side of Sizzler. When a knuckleball specialist is on, he's a magician, conjuring the dark and mysterious forces of the universe; when he's off, he's the pot-bellied assistant manager throwing batting practice…

Throughout the history of Major League Baseball, only one or two knuckleball pitchers have tended to play at any one time, which keeps the pitch on the endangered species list. Stern and Sundberg have done well to round up all the living knuckleballers for interviews, including old-timers like Phil Niekro, Charlie Hough and Jim Bouton, whose classic book Ball Four details his efforts to develop the knuckler when his other pitches faltered.

Watch the kooky pitch in action here.