Over the weekend, I was watching a European Tour tournament on the Golf Channel. The announcers talked about a player who was disqualified because his ball moved (I didn't hear whether due to slope or wind) after he placed the ball on the green in front of his marker. With his marker still on the green, the player thought he could pick up the ball and replace the ball.
His competitor complained to the Committee that the player should not have replaced the ball. The Committee agreed and disqualified the player because the competitor didn't say anything until after the player had signed and turned in a later discovered incorrect scorecard, i.e. without the two-stroke penalty for touching his ball in play. (It would have been nice if his competitor told the player and got the ruling before the player turned in his scorecard. As it was, the player was disqualified for turning in an incorrect scorecard.)
I went to the USGA Decisions on the Rules of Golf and found Decision 20-4/1, which states that a ball is in play when it is replaced, whether or not the marker has been removed. Thus, the ball must be played from the new position.
I have to admit that I might have done the same thing as the player. I would have thought since my marker is still on the green, that I could replace the ball after it moved inadvertently.
Besides seeing great golf, I enjoy watching tournaments because I often learn swing tips or rules I otherwise might not have known.