I have no idea where I read this, but in those days, the defense was rewarded for getting a red zone stop by getting the ball at the 20, but that rule was obviously repealed somewhere along the line.
EDIT: Jerry Markbreit talked about this rule in a column he wrote in 2003 for the Chicago Tribune.
We've got a rules debate going on and need an expert clarification. When the offensive team has a fourth down inside the opponent's 20-yard line and throws an incomplete pass into the end zone, where does the other team take over on downs? I always thought it came out to the 20-yard line, just like a touchback, but my friend insists it is spotted at the previous line of scrimmage. Can you tell us which one of us is correct? Is the rule different between the NFL and college? No dollars are riding on this, just bragging rights. -- Seth Greeley, HoustonMore than 30 years ago, the NFL rule stated that a fourth down incomplete pass into the opponent's end zone would result in a touchback if the ball was snapped from somewhere inside the 20-yard line. That rule was changed and it presently states that a fourth down incomplete pass into an opponent's end zone will be returned to the previous line of scrimmage, wherever it might be, with a first and ten from that spot for the defensive team. The collegiate rule is the same as the NFL rule.https://www.chicagotribune.com/cs-031231jerrymarkbreitsanswers-story.html
