Rules Challenge

Brian got it right.  A dropped ball may only be re-dropped in accordance with Rule 20-2c. There is no provision for a ball dropped under Rule 28c (Ball Unplayable) to be re-dropped, unless it rolls more 2 club lengths from where the dropped ball first strikes the course or rolls nearer the hole.  In this situation, this did not occur as it rolled back to the same spot.

The lesson here is, if you deem your ball unplayable, carefully consider all your options (you have 3 of them) and look carefully where you are going to drop the ball and where the ball may roll, after it is dropped.  It is too late once you drop the ball.

Bruce was correct.  To understand why, we first need to look at the definition of a provisional ball, which states, it is a ball played under Rule 27-2, for a ball, that may be lost outside a water hazard or may be out of bounds. 

That means there are only two situations where you can play a provisional ball.  The first is if you think that your ball may be out of bounds. The second is when you think that your ball may be lost, but only if you think it may be lost out of a water hazard.  You cannot play a provisional ball for a ball that you think may be lost in a water hazard.

In this situation, if there was a possibility that the ball was lost outside the hazard, a provisional ball could have been played, but it should have been announced and then played from the tee.  Rule 27-2 says, a provisional ball must be played before the player goes forward (more than 50 yards) to search for his original ball.

As soon as Tom left the tee and moved forward more that 50 yards, he was no longer entitled to play a provisional ball.  For these reasons, when Tom dropped another bal, it was not a provisional ball.  It became the ball in play, with a penalty of one stroke. If Tom then found his original ball, it would no longer be the ball in play, so hitting the original ball would have incurred a further penalty of two strokes, as it would be deemed the player had hit a wrong ball.