Here’s an example why!
In a stroke play event a Player (A) asks his fellow-competitor (B) if he might mark his (B’s) ball in order to save time. Player B agrees. Player A sets B’s ball aside and then putts out. Player B then putts out from where his ball lay on the green – forgetting that he had agreed to let Player A mark his ball. One might be forgiven for thinking that Player B has played from a Wrong Place (Rule 20-7) and therefore incurred a two stroke penalty.
However, upon closer examination of the facts, and secure in the knowledge of our Definitions, we find that Player B has not played from a Wrong Place, but in fact has played a Wrong Ball, as Player B’s ball was out of play as soon as it was marked and lifted.
In the case of a Wrong Ball situation the error MUST be corrected before teeing off from the next tee or the two stroke penalty for playing a Wrong Ball becomes a case of DISQUALIFICATION for not correcting the error before teeing off at the next tee.
A couple of points come out of this incident:
LEARN THE DEFINITIONS!
As soon as you mark and lift a ball, it is OUT OF PLAY.
Decision 15-3b/3 amplifies the above.
Q. In stroke play, B marked the position of A's ball on the putting green, lifted it and placed it nearby on the green. A failed to replace the ball. He putted it from where it lay and holed out. The error was then discovered. What is the ruling?
A. When a ball is lifted, it is out of play – see Definition of “Ball in Play”. When A played a stroke with his ball which was out of play, he played a wrong ball.
If A knew that B had lifted his ball, he incurred a penalty of two strokes under Rule 15-3b and was required to replace his ball on the correct spot and play out the hole.
If A did not know that B had lifted his ball, A could not be penalised for playing a wrong ball. If he became aware of the mistake before playing from the next tee, he was required to replace his ball on the correct spot, without penalty, and complete the hole. If he learned of the mistake after playing from the next tee, the score with the wrong ball would stand and there would be no penalty.