||The way to catch a knuckleball is to wait until it stops rolling and pick it up.
|— Bob Uecker
As with hitters, the unpredictable motion of the knuckleball makes it one of the most difficult pitches for catchers to handle, and they tend to be charged with a significantly higher number of passed balls. Former catcher Bob Uecker, who caught for Phil Niekro, said, "The way to catch a knuckleball is to wait until it stops rolling and pick it up." Bouton said, "Catchers hate it. Nobody likes to warm up with you." According to Adair, the 150 ms minimum human reaction time may be too slow to adjust to a knuckleball's changing direction.
A team will sometimes employ a catcher solely for games started by a knuckleballer. The "knuckleball catcher" is equipped with an oversized knuckleball catcher's mitt, similar to a first baseman's glove; Doug Mirabelli, formerly of the Red Sox, used a softball catcher's mitt. The Boston Red Sox did this fairly systematically in their 2004 world championship season, with Mirabelli regularly catching in place of Jason Varitek when Tim Wakefield was pitching. This use of a "specialist" catcher continued into the 2008 season following the signing of Kevin Cash, and 2009 saw George Kottaras fulfill this role. On August 26, the first time Victor Martinez caught Wakefield, he used a first baseman's glove, instead of a regular catcher's mitt. For a catcher, a key disadvantage to using a first baseman's glove instead of a regular catcher's mitt is that first baseman's gloves are not designed for easy extraction of a ball from the glove, a trait which further intensifies the difficulty a catcher endures in preventing baserunners from stealing bases.
On occasion, teams have traded knuckleball pitchers and their catchers in the same transaction. For example, Josh Thole and Mike Nickeas went with Dickey when the pitcher was traded to the Toronto Blue Jays in late 2012, and the team later signed Henry Blanco, who also caught for Dickey.
The record for passed balls in an inning (4 passed balls) was first set by Ray Katt of the New York Giants in 1954, catching Hoyt Wilhelm. It was tied by
Geno Petralli of the Texas Rangers in 1987 while trying to catch knuckleball pitcher Charlie Hough, and tied again in 2013 when Ryan Lavarnway of the Boston Red Sox passed four balls in the first inning, catching knuckleballer Steven Wright in Wright's first major league start. Varitek holds the postseason record with three passed balls in the 13th inning of Game 5 of the 2004 American League Championship Series while catching Wakefield.
In the 2013 season, J. P. Arencibia (then catching for the Toronto Blue Jays) set a franchise record by allowing 4 passed balls in the season opening game (a 4–2 loss) while catching for knuckleballer R.A. Dickey. He never caught for Dickey again.