Case book 5.3.3
 

The way I understand this situation is that if the offense doesn't convert on a 4th down pass, the ball is placed "as it was" before the down for the new offense, thus giving the new offense the length of the football without earning it.
However, if the offense doesn't convert on a 4th down run, the position of the ball is moved back the distance of the football (11 1/2 inches)so the new offense must earn the distance of the football.
Why is this not the case with the incomplete 4th down pass? Or am I reading this situation wrong.

You're reading it incorrectly. In neither case do you move the ball following a loss of possession on downs. Don't get hung up on the forward tip of the ball being the spot. The position of the ball is what's important. We only use the tip of the ball for measurement purposes. It might be easier to think of the neutral zone. Both teams are restricted from entering this space and it doesn't move following a change of possession.

I don't have my case book at work so I'm not sure if that's where you're getting this. It doesn't seem right. If you measure after a 4th down and they're short you wouldn't move the ball.

The only time I can think of where the ball is being moved is when they are coming out of their own end zone and barely avoid the safety with the ball laying "sideways". When you rotate the ball 90 degrees to set it you can't have the back end in the EZ so they gain a few inches.

Other than that I believe the ball is where the ball is and you set the chains to it.

In the case of an incomplete pass on fourth down the ball is moved back to the down indicator and the forward point of the ball placed at this marker. No yardage is gained. On a run your marking the spot at the end of the run and moving the chains for the new series. AM is right about assuring the back of the ball is off the endline so doesnt break the plane before the snap

Just remember this, move the chains, not the ball. Place the ball where it belongs following whatever play is run, then reset the chains if a new series is not earned.

Adding to what Rick is saying, on an incomplete pass, the ball will be put back to the PS, and the chains moved the length of the ball cuz the LTG is 10 yards from the forward point of the ball.

On a 4th down running play that does not earn a new down, the chains will always move and have be at the forward point of the ball for the new series for B.

Example
 

A's ball, 4th and goal. A30 runs the ball and is stopped short at the 6-inch line. Team A lost the ball on downs. Team B will put the ball in play with the tail of the ball now 6 inches from the goal line. The back stake will mark the spot at approx. the 1/2 yard line (6 in + 11 1/2 inches = 17 1/2 in).

You can't reverse the ball in this situation because you'd be placing half of the ball in the end zone. This situation highlights the fact that you don't move the ball on any other situation following a loss of possession on downs.

I believe I was reading way to far into this situation and just confusing myself. Rick, you said to place the ball where it was and just worry about moving the chains to the front point of the football. That would make the most sense to me. And I think I'll skip reading that situation from now on.

Thanks