Bill Connelly made some similar points in his article this week:
Indeed, all the major offensive measures are down compared with where they were this time last year. In Week 1 of last season, in FBS vs. FBS games, teams averaged 2.11 points per drive and 5.52 yards per play; this year it was 1.9 points per drive and 5.4 yards per play
So what's the problem? Big plays vanished: The percentage of completions gaining at least 20 yards fell from 16.3% to 14.7%, and despite the uptick in completion rate (and the downtick in sacks), average yards per dropback fell from 6.4 to 6.0. You know how pro defenses adapted to force Patrick Mahomes to settle for checkdown after checkdown because they were basically forming an umbrella at the back? It appears college defenses are doing the same thing. They're forcing quarterbacks -- who, on average, are less experienced than in recent years -- to dink and dunk and score points before making a crippling error or coming up short on third down. It's working.