text: If, during an attempt to execute the "hidden ball trick" (where the defensive team deceives the runner(s) as to the ball's location while the play is live), the pitcher stands on the rubber prior to the fielder revealing the ball and applying the tag, the runner is not out.  Instead, it is a balk, with all runners on base being awarded their next base.
  Common misconceptions
  "Catcher's balk" is not a term in the official rules, but is sometimes used to describe an atypical situation relating to an intentional walk: if the catcher is not completely within the catcher's box when the pitcher releases the ball during delivery, it is a violation. The balk is still charged to the pitcher, because such a pitch is defined as a "Pitcher Illegal Action."
  A pitcher is not required to step off the rubber before throwing to an occupied base in a pick-off attempt. With one foot on the rubber in either the windup position or the "set" position, the pitcher may either: 1) deliver the ball to the batter: 2) throw to a base for a pickoff; or 3) step off the rubber.
  MLB rules state that: "Pitchers shall take signs from the catcher while in contact with the pitcher’s plate" (the rubber), but the rules do not describe the infraction as a balk.
  Major League Baseball balk records
  Steve Carlton had 90 balks during his major league career.