To be fair, the reason we did so well this year is because the defense made huge strides forward. We had just as explosive an offense last year, but the trainwreck that was our secondary cost us the two biggest games of the season (MSU, Clemson) and almost blew The Game. I'm in agreement with Johnny that the general trend in CFB is away from under-center run-first clock-suffocating Tresselball (RIP Senator) as even evidenced in Tuscaloosa. As such, these offenses have been putting their counterpart defenses in tougher positions (the hurry-up means that the D sees the field longer, as drives no longer kill clock as before, the proliferation of larger holes in spread-out formations increase the chances of explosive plays and cutback lanes, bigger point leads mean teams will pass with impunity as the game goes on, etc etc).
In response, defenses have adapted to increasing takeaways, bending-not-breaking, and limiting big plays, rather than shutting down opponents completely (apologies to Wisconsin). That mentality shift means that the definition of a good defense has changed as well, given the limitations they have to work with. When statistically measured against their comparison cohorts from yesteryear, it may appear that this version of the Silver Bullets has been hemorrhaging yards, but with what they've had to work with, they've been simply outstanding. Though they gave up 465 total yards to the Ducks, along with 4 turnovers gifted by the O, holding Oregon to only 20 points is a minor miracle in my eyes and worthy of standing among some of the great historic Buckeye defenses.