Prior to 1978, defenders were allowed more contact with receivers, and that loosened up the short passing game as well. That helped with the fourth quarter comebacks.

Was thinking the same thing (see my post below). They’d gotten away from the pass so much, that perhaps teams weren’t equipped as much to make those quick strikes, besides throwing bombs and Hail Mary’s of course. Totally off the top of my head right now, but it seems like we just didn’t see those types of methodical, game-winning drives again (the numbers are higher in the 1960’s, so perhaps we can assume that Johnny U and those guys were passing more to get that 4th quarter win) until Montana, Elway, etc., in the 1980’s? Maybe I’m stretching things here…