Complex sentence: 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 when a knuckleball pitcher is on the mound.
Split into simpler sentences: As with hitters, the unpredictable motion of the knuckleball makes it one of the most difficult pitches for a catcher to handle. Catchers tend to be charged with a significantly higher number of passed balls when a knuckleball pitcher is on the mound.