• courtesy of FilmBuff

Behold the mysterious knuckleball.

Unlike baseball’s other pitches — the fastball, the curve, the slider — the knuckleball does not rely on spin and velocity to defeat hitters at the plate. Instead, the knuckleball floats in at a slacker’s pace (60-70 mph, usually, as opposed to the fastball’s 90 mph range) and ideally doesn’t spin at all. That lack of spin causes interesting things to happen to the air currents around the ball as it travels to the plate. It swerves and dips, flutters and dives.

The new documentary Knuckleball, new to DVD and digital this week, is a fascinating film for even casual fans of America’s pastime. Veteran documentarians Ricki Stern and Annie Sundberg (Joan Rivers: A Piece of Work) explore the history of baseball’s weirdest pitch by profiling MLB knuckleballers Tim Wakefield and R.A. Dickey during the 2011 baseball season. They also dig into baseball’s past with former knuckleball masters Charlie Hough, Wilbur Wood, Jim Bouton, Tom Candiotti and Hall of Famer Phil Niekro.

Throwing an effective knuckleball in the big leagues is such a hard thing to do that, in the entire history of the game, only a few dozen players have ever made a living at it. With the retirement of Boston’s Tim Wakefield after the 2011 season, the lone knuckleballer in baseball is R.A. Dickey, who won last year’s Cy Young award with the Mets. Dickey is the first knuckleballer ever to earn that prestigious honor. His reward? Getting traded to the Toronto Blue Jays in the offseason. The guys will tell you, knuckleballers get no respect.

Dickey is the film’s strongest and most charismatic presence — an articulate, unassuming guy who has evident respect for history and culture of baseball. His story is especially compelling, as he transforms himself from a washed-up traditional pitcher into the game’s last remaining Jedi master of the knuckleball. He’s like Yoda now, out there in the Dagobah swamps of Toronto.

The DVD edition of Knuckleball comes with two hours of bonus materials, including additional and extended interviews, plus featurettes on famous knuckleball moments in baseball history. You also get more details on the weird science behind the pitch. If you’re interested in mining this extra material, be aware that you may not get all of it, or even any of it, via the usual digital download and video-on-demand systems. Read the fine print.

Also New This Week:

Paul Giamatti headlines the surreal horror-comedy John Dies at the End, from the director of Phantasm, The Beastmaster and the enduring cult classic Bubba Ho-Tep.

Based on the 1970s British TV series, the UK action film The Sweeney stars Ray Winstone and Ben Drew as hardcase London cops squaring of against the usual lot of nefarious Eastern European gangsters.

Clive Owen and Nicole Kidman star in Hemingway & Gellhorn, the HBO original movie about the famous literary couple.