Rule 5-1- (CB 5.1.2E Comment) tell us that when a dead ball foul is committed prior to the next ready for play, the penalty is enforced prior to setting the chains; and the subsequent first down is to be 1/10. So in AB's play:
1. A made the line to gain = = 1/10 for A from B15;
2. DB Illegal snap (PRIOR TO THE READY) moves the ball AND THE CHAINS (if correctly handled) to the B20 = 1/10 for A from B20. Line to gain should now be the B10.
3. So, after A runs the FIRST of the 4 plays that AB lists, they HAVE ALREADY reached the required LTG - regardless of where the chains were improperly set. AND...
4. CB 5.1.1B tells us that improperly set chains are correctable only until the next legal snap.
5. So AB is correct that after the "discovery" that the chains were improperly set (which now has no bearing), and before the current series of downs has ended, under the new rule, the R has the ability to correct the down error; and it should be 4th and goal for A at the B4.
.....I think
I'm not a football ref, but I love to lurk and I love good logic problems. The only information I'm working with here is AB's scenario and Curious's comments on it. Any rules errors are from pure ignorance.
1. Chains are set at the B15 and the line to gain is the B5.
2. DOG foul occurs before the RFP.
3. Line of Scrimmage is properly moved to the B20. Chains are improperly left at the B15. LtG is properly B10, improperly shown as B5.
1/10 @ B20 gains 11 yards to B9 for what should be a first down but is improperly shown as 4 yards short of LtG. (Is
this the next legal snap or the down in which the chains were incorrectly set? I'm assuming the later.)
4. The proper down is 1st Down @ B9. The down shown is 2nd. The LtG is properly the goal line but improperly shown as the B5.
1/G (shown as 2/4) is an incomplete pass.
5. The chains are sanitized under 5.1.1B and the LtG changes from the goal line to the 4.
2/4 (shown as 3/4) is an incomplete pass.
3/4 (shown as 4/4) is a gain of 5 yards to B4.
The result of the play is First and Goal, despite the error in downs and incorrectly set chains.