This is an interesting documentary for baseball fans. Much of the iconic attributions to baseball's knuckle-ballers has been made before by sportscasters during games, but this is fun to watch nonetheless. The movie focuses on two pitchers in 2011, Tim Wakefield, and R.A. Dickey. I believe Dickey is still pitching in 2013 for the Blue Jays.
There is a tendency in documentary filmmaking to include too much footage, and "Knuckleball" is no different. The documentary jumps back and forth in time rather than follow a chronological order. The same crowd shots are used multiple times. There is footage of the pitchers driving around in cars. There is a lot of game footage of the two pitchers which becomes tiresome after an hour. Just when you think there is going to be some breakthrough or change of pace in the film, it lapses back into footage from the mid 2000's. There is excessive coverage of the Red Sox-Yankees series.
This movie would be good for people who aren't familiar with pitching styles or the history of the famous knuckle-ballers in baseball.
There are entertaining interviews with Niekro, Hough, and Wilbur Wood.
In short, this documentary is about 15 minutes too long. It is a good bet for serious baseball fans.